Early rebuy decisions when rebuy chips are at a discount

[SumZero]

So how much the worse of it should you be willing to take on a gamble it up strategy when the rebuy chips are at a discount relative to the starting chips (I didn't see this discussed in the MTT collective wisdom thread and couldn't find it in an MTT search for rebuy so sorry if this is a FAQ)?

I've started to play in a live $40+9 tournaments that gives you T$500 w/ unlimited $20 rebuys ($500 chips) and a $40/T$1000 chips. I'm more used to rebuy tournaments online where the rebuy amount costs the same as the initial buyin and gives you the same chips.

Today I think I made a really bad decision on the following hand:

level 2 - blinds 20/40 and 11 handed. Many players didn't rebuy at first and have just $500, but a couple of players have doubled up through players who rebuy $500 at a time. I have $1100 (I did the immediate rebuy). UTG player has the second most chips at the table, around $3500, and moves all-in. UTG player hasn't made this move before and has been in only one pot, a big one, that he won when his limped in 44 turned a 4 after a player with a K slowplayed a KKx flop. I'm in MP and see AKo. I think his most likely cards are pocket pairs in the range JJ-99, but this was just a guess at the time, no real knowledge as it could be AA or KK figuring that he'll get loose calls. I do the calclulations ignoring the rebuy and figure 1100 risked to win 2260 doesn't seem like the right odds to take the worse end of a coinflip, plus there is some chance I'm dominated - I think more than the chance that I have him dominated. I fold. Another player at the table calls w/ A7o and the UTG raiser had 99. He made the same move two other times later during the rebuy period and once wasn't called and once had JJ and was called by TT and AQo. He won all 3 hands.

Now if it was a freeze out tournament I think my fold of the AKo there might be justified (it would be close, but I think it is ok). But in the rebuy tournamnet, especially when chips were "half-price" for the rebuy (which is really like for $40 I'd get what cost me $60+9 the first time) then it makes sense to take the worse of it given the rebuy since likely EV(1100) < (.447 * EV(2260) + .553 * (EV(1000) - $40)).

So when you are around the initial chip amount (including first rebuy) how much the worse of it should you take to gamble it up knowing if you lose the chips are cheaper. Should you take a 3:2 underdog for even money given the chips cost 3:2? Like if you were last to act and he showed you his cards and he had A9s and you had QTo not in his suit should you call?