Interesting thread...
I particularly like the comments from Smart Money....
I'm mainly a cash player, but I can't understand this logic.
If you push the turn, I can't see any of the hands you're beating folding. Likewise AK/AQ hands won't be calling you.
Whereas by check/calling his all-in, you're still losing to any hands that are ahead of you of course, but you also put yourself in a favourable position over hands that are trailing your 99, including a bluff attempt.
I am almost exclusively a tournament player and my mentality is completely different. The fundamental of successful tournament play is SURVIVAL. Making money/chips is a secondary consideration. This is so because clearly you can't make money if you've been knocked out. In cash play survival is not an issue...it's all about making $$. So the two mentalities are completely at odds with each other.
To answer the points you raise M3...
Point 1) - Do you agree that a push when the 8 arrives is a better play?
Absolutely yes. You have decided to play the 9-9 here and have hit an almost perfect flop...(or as perfect as tournament time pressures allow). The only danger is the BB holding a deuce and you quickly find out that this is not a factor so I now feel almost certain you have the best hand.
You bet out and the other limper IMMEDIATELY CALLS. This tells me he does not have a BIG HAND. There is another active player in the BB behind him and there would be at least some consideration from him with regards to how he is going to proceed here....does he want to rope in the BB? This would require some element of thought. The immediate call also tells me he doesn't have an over-pair. Why? Again he has the same active player and also yourself to consider. A hand such as J-J is vulnerable in a multi-way pot so if he didn't raise pre-flop he would certainly raise now.
In tournaments I ALWAYS press hands that I think are ahead but I feel are vulnerable. Getting tricky here and taking your foot off the gas can lead you into either out-draw or tough decision making territory. And I absolutely hate calling all my chips in with the worst hand. So I definitely move on the turn. In situations like this my opponent is going to have to show me a hand that beats me. If he can then fair play....but like you say...it will be his decision to make not mine. You may not make as much as you could if you avoid playing this hand in the trappy way you have but remember the key in tournaments is survival and this point is particularly prudent with marginal hands.
The only downside to this hand is the fact that you didn't raise. I absolutely hate going broke in an un-raised pot. If I had raised pre-flop I push the turn with confidence. In this un-raised pot I simply push and hope I reach 5 seconds without hearing "call"....and then relax.
Point 2) - Do you call the all in?
Absolutely yes. Don't like this anywhere near as much as pushing myself. But I believe I have the best hand. There is absolutely no way he has 5-5 or 8-8 or any hand as big as this. Any change of behaviour during a hand is suspicious. If he flopped a boat he slow-played by calling...why would he suddenly change that strategy on the turn and quickly push. Slow play - Quick play is a big tell for me. Either he is trying to rope you in or push you out. Which is it? The fact he can't decide along with the pre-flop limp (after a limp) and the immediate post-flop call makes me think he's weak here.
Point 3) - What do you think the likely holding of the other limper is.
I like the idea of a suited 3-4 here. A limp after a limp pre-flop. An immediate call when he picks up the open-ended straight draw and the sudden change in attitude to move all-in and expose your "weakness" (with outs) on the turn.
If the chips go in on his terms now and he gets lucky you have not survived because of your trappy play. By checking the turn you have been put to an awkward decision for all your chips and probably folded the best hand.
Out of interest...what did the bugger have M3?
Good Luck