This is a type of hand that I absolutely hate in PLO - since unimproved Aces win so rarely in this game, I don't know if I should bet or not...

Poker Stars
Pot Limit Omaha Ring game
Blinds: $0.05/$0.10
9 players


Stack sizes:
UTG: $9
Hero: $11.75
MP1: $3.70
MP2: $6.55
MP3: $8.35
CO: $7.40
Button: $6.95
SB: $2.50
BB: $4

Pre-flop: (9 players) Hero is UTG+1 with
UTG folds, Hero calls, MP1 calls, MP2 folds, MP3 calls, CO calls, Button calls, SB raises to $0.75, BB calls, Hero calls, MP1 folds, MP3 calls, CO folds, Button calls.

Flop: ($3.95, 5 players)
SB is all-in $1.7, BB calls, Hero calls, MP3 folds, Button calls.

Turn: ($10.75, 3 players + 1 all-in - Main pot: $10.75)
BB checks, Hero checks, Button checks.

River: ($10.75, 3 players + 1 all-in - Main pot: $10.75)
BB checks, Hero checks, Button checks.

Results:
Final pot: $10.75

*** SUMMARY ***
Total pot $11 | Rake $0.50
Board [7c 5d 9h 3s Kd]
Seat 1: BigPun23 folded before Flop (didn't bet)
Seat 2: stinkay folded on the Flop
Seat 3: miami-T folded before Flop
Seat 4: iplayAAonly (button) mucked [4d Ah 8h 7h]
Seat 5: rogate (small blind) showed [2h Qh 9d Qs] and lost with a pair of Queens
Seat 6: badd dog 77 (big blind) mucked [4s 8c Qc Ts]
Seat 7: #1Roley folded before Flop (didn't bet)
Seat 8: stickdude90 showed [2c Ad Ac 7d] and won ($10.50) with a pair of Aces
Seat 9: scooter00707 folded before Flop

pf reraise and push flop.

use the aces to bully.

Re-raising is a definite option, although I don't think it's obligatory. If you wanted to get really "clever" in this case, you could also minimum re-raise, which means that SB almost has to push but has just enough stack to allow you to re-raise again if any of the big stacks have come along for the ride.

If you don't re-raise, I'm not very fond of this board in a pot that multi-way. What you're looking for imo on unimproved AA is an uncoordinated board. On this one, you have a straight already staring you in the face. The only real consolation is that both of your suits are at least present (giving you 2 runner-runner flush draws). And it's SB who is betting and is essentially pot-committed anyway. I'm not giving him credit for a made straight in any case.

Anyhow, if you end up playing it multi-way, I think you're looking for top set or one of your flush draws, all of which you've missed. I don't think it's bad to call the flop for 1/2 pot in the hope of turning a flush draw (also, if everyone else folds, I think there's a good chance you're ahead of SB). But I think you HAVE to check it down from there barring improvement.