With a bot, I figured there was no hope of bidding 7H intelligently In fact, my feeling is that (among all hands partner might hold) 6H will go down more than 7H will make. On his actual hand, even though you did go down only because clubs were 5-2, but you really needed far more than that.
Dummy was
S-KJxx
H-J10x
D-J10xxx
C-x
So at minimum you need clubs 4-3. If all that works, you still need trumps 2-2 to make 7 hearts, because after ruffing 2 clubs you have only the J left, so you’ll lose if someone has Qxx or a stiff Q. (Double dummy you could pick up Qxx onside if LHO’s stiff were the 10.)
But as you say, the actual hand proves nothing. Many hands will make 7H. Many hands won’t. My thinking was that whenever partner has 3 clubs without the Q, you don’t want to be in 7. At best he has J10 of clubs, but then you’re on a finesse.
Also, you may well have a trump loser. Even if he has Qxx, you do if trumps are 4-0, and if he has four hearts without the Q you might need trumps 2-1. (Though with J10xx in dummy you could pick up 3-0 onside.)
lost by 3 to NN. Won by 13 vs AA. Both reissued.
5-ways are over until tomorrow. Provisionally I’m postive in one, deservedly - in the other. Or maybe not deservedly, since it was supposed to be a Declare-only, but I set it up wrong again. I’m minus in it mainly not due to any bad declarer play, or even bad bidding, but to a horrendous defense. In Declare-only, I couldn’t misdefend.
oirg wins one group challenge with +29.75, not quite a margin of 10. NN wins the other with +20, a margin over 20 since his was the only positive imp score.
Both reissued, one correctly as a Declare only this time.
bridgebase has not been working well for me for the past few days, but I have managed to complete the challenges.
Lost to NN by 16. Beat AA by 13. it looks like procrastinator did not play any board in our 2-way. I had some reasonable results, but also butchered a defense and let 1N X make instead of down 1 vul.
In the regular 5-way, I won with +19.25. In the declare-only, NN won with +18.25. Neither was a margin of 10.
All reissued.
I was having BBO trouble too, but I did not have a 2-way match listed, weird. Have a new one now, so hopefully issued are resolved.
Lost by 14 to NN. 13 on those where, strange as it will seem, I ended up taking a spade hook for the trump 9, not at all confident it would win, in a 6S slam when I was playing a 5-3 spade fit including the top 5, and where I believe my line of play was correct (and the finesse won, making 7). Lost imps because he was in 7 spades, making, without that finesse.
spoilertext
It isn’t hard to make 7 with the lie so favorable. In 6, you are cold (on the actual DQ lead) on a crossruff as long as clubs are at worst 5-2, diamonds at worst 5-3, hearts at worst 4-2. Take the diamond ace, cash club ace, two high hearts, diamond K and a ruff, club ruff.
Leaving dummy S-AJ H-Jxx D-x
My hand S-KQ108 H- D- C-Qx
I have the rest if I can guess which red suit I can safely ruff, then high crossruff, but down if my trump 8 gets overruffed and LHO leads another trump. So don’t risk the overruff. Crossruff the next 4 tricks high, leaving lead in dummy with 2 red cards, me with K8 of spades, and RHO with 9x remaining can’t stop me from winning both.
Then AAAGH. Lost by 6 to procrastinator when I misclicked, intending to claim a game exactly making, but instead conceded down 3 for -11 imps.
Both reissued.
NN wins the Declare-only with +15.50, a margin over 10. I beat AA in a 2-way by 35. Both reissued.
Lots of boards without many large swings. Beat NN by 4 with no swing over 5 imps in 16 boards. Lose to procrastinator in a match with only 1 swing of any size in 16 boards: 12 imps to him when I misdefended a game. Both reissued.
procrastinator wins the regular 5-way with +28.25, not a margin of 10. Reissued.
:swear: lose to AA by 2, based on strange bidding (IMO) by LHO. Unfavorable vul for the bot, who holds 
He hears P (by his LHO) - P - 1C (by us, his RHO) - 2NT - 3C - 3D - something by us - ?
When something was P (by me), he thought his hand was worth 4H. When something was 4C (by AA), he passed. That pair of choices seems strange to me. Reissued
Lose to NN by 20. Reissued
I win regular group challenge with +13.25, not a margin of 10. Procrastinator wins Declare-only with +15.50, a margin of 10. I lose to AA by 14 and to procrastinator by 26. All reissued.
Lose to NN by 22, to procrastinator by 19. Both reissued.
AA wins the regular group challenge with +23.25, a margin over 10. I win the Declare-only with +8.50, not by 10.
I lose 2-way to AA by 5. All reissued.
Some interesting hands in the one I won. Two that I played a bit more aggressively that resulted in my winning the group. Usually my extra aggression lands me in last place.
One was the competitive auction that everyone else ended up defending in a doubled spade contract (and almost everyone set), but where I made a 3NT bid despite having no spades myself, and then had both Ks land in the right spot to make 3NT+4!
The second was a strong spade hand that I pushed to 6S despite having modest HCP but good distribution. Everyone else stopped at 4S.
Hands 7 and 11, for reference.
I managed to not only miss 3NT, but to allow 3Sx to make.
I am not impressed with partner’s double. He already bid 1NT, so I know he has a spade stopper, IMO x should should more like KT9x in spades. My thinking on passing was that partner had a better picture of my hand then I did of his (before the double), so no reason to overrule his decision. Obviously not a success this time, but think I would make the same decision again.
On the hand you bid to 6S, I did consider rebidding 3S instead of 2, but ended up taking the low road, certainly think your bidding was reasonable. I will note that it is not a great slam though: often off ace of clubs and a club ruff off the top.
What you’re saying makes sense. Regarding stretching to game or slam, feels like the reward warrants some level of risk. Clearly there is some math, and someone may lay that out in this case, but I’m typically happy to have a 50/50 shot at slam/game stretch.
Yeah, 50/50 is typically the breakeven point. Only exception is that vul at IMPs, game vs partscore, the IMP odds are such that you should bid a game if it is 37% (realistically a bit higher, since that 37% assumes you never get doubled or go down more than 1).
In my experience folks seem to want to be in 50% games even though mathematically it is break even (NV or MPs), but are indifferent to 50% slams. Not exactly sure why that is, seems almost cultural.
results since the last report:
I win a regular group with +3.34. procrastinator wins the declare only with +15.00. Neither by 10.
I lose to procrastinator by 18, beat AA by 15, beat NN by 2.
All reissued, except that I just noticed the regular group challenge is only 8 boards this time. It ends tomorrow, so some have likely played, so I’m leaving it 8 rather than canceling and reissuing now.
ETA: beat procrastinator by 5, including a push where each of us defeated a 6NT contract. Saying we defeated it is a bit of a misnomer, since declarer was cold for 6NT if he could get at least 3 heart tricks from a suit of AJx opposite K10xx, even if he lost one in the process, so long as he didn’t lose a diamond trick before establishing a third heart trick. Reissued.
I don’t see the Declare-only challenge. Maybe it expired before I finished, maybe before I even started. Someone else can announce the results. I’ll reissue the challenge.