There is no guarantee you will get the 2nd TD or stop the other team from scoring again.
If either of these events happen, the question is moot.
The results are what I figured (75% say go for 1 now). Here's my explanation for why I would go for 2 now.
What if you wait to go for 2 until the second TD and miss. Then you have to onside kick and get the ball back. IOW, you have to panic because you had been playing as if it was a one possession game but the game turned into a 2-possession game as soon as you miss the 2-point conversion.
Contrast that with going for 2 now:
If you make it, you are about 99% sure (the XP conversion rate) that it's a one possession game now.
If you miss it, you are now 100% sure that it's a two possession game. Thus you play accordingly.
The problem with going for 1 now is that you play as if it's a one possession game (OK with letting the other team kill time; letting the clock go down when you have the ball). Yet you don't KNOW that it's a one possession game. The likely result of you waiting to go for two is that you score the TD to make it 29-27 with less than a minute left, then you panic if you miss the conversion.
If you know it's a two possession game, you try to score as quickly as you can because you know for certainty that you need to score twice.
Wouldn't you rather know if it's a one or two possession game now rather than having only a 40% chance of it being a one possession game?