I came across this spot now a few times. I play on a client where the MysteryKO hits in at the end of late reg. Lot's of small stacks enter the tournament in the last 5/10min before closing and obviously there are always small(er) stacks throughout the game.

How do I calculate when it is profitable to bust a shortstack close to the start of the KO stage? What amount of % adding to my stack put against the opportinuty of busting a player with KO a few hands later. Is this something I even should take in consideration? I see 95% of the people just calling shoves from smallstack close to, but before the start of, the MysteryKO stage.

So, before the bounty stage, I would just play like normal in this situation - just take +EV spots against short stacks if they come.

If the bounties start later (where I play, sometimes the mystery bounty starts on the third level after late registration; sometimes it starts in the money), then there's sometimes a benefit in not busting a micro stack and waiting for the bounty stage to begin so you can try to scoop up that short stack bounty. Here, though, they can just rebuy, so that's not a concern.

Some players will take any gamble they can to try to build a big stack, but I think that's a mistake. You're risking giving away chips you could use to try to win bounties, for the hope of... winning chips you could use to try to win bounties. There might actually be a little FGS factor here to lean you to not take those gambles right before the bounties start, because it's so much more profitable to put your chips at risk for those bounties.

ICM is into play even more in this stage, eventough its not yet ITM or in the KO phase. I just am unable to calculate when it is profitable to fold of r/f vs shortstacks in this stage so close to to KO stage.

By the end of late registration, there's usually about half the field left, maybe a little less. So ICM is always a factor, but if you're talking about calling short stack all-ins without really putting yourself at risk, it's relatively minimal. Don't go too far out of your way to deviate from the minor ICM adjustments either way, and you'll probably be fine. (If you do deviate, I would deviate on the side of caution. But not too much-- if ICM says you need a 52% edge to break even on a 50/50 shot, you might pass on 53%, but definitely don't pass on 60%.)