The only reason we are playing A7 here is to flop 2 pair and get it in vs something like A-T or AAx, 77x. As this won't happen often enough I think you need more than 6:1 to play this
Since this happens about 5% of the time, you need 19:1 to play this...
Additionally, with our biggest effective stack at
30 big blinds deep (and two of them smaller than that), we have far less implied odds than you think.
And furthermore, think about the hands people play in limped pots. A7o flops like trash against small pairs, suited connectors. The only time they're going to put money in the pot against you is when they're putting you in a horrible RIO spot.
What we should be thinking about doing is raising big preflop to take the dead money the limpers are putting in the pot. I'd rather do that than call in a big way. Limping here is pure spew. I don't have math to back me up, because doing it would be REALLY long & complicated. But if you check hold'em manager and run a filter for when you play in spots like this, I'm sure its a horribly losing spot.
What you're looking at is the preflop play and going "oh, I'm only losing 400". But you're not! You're setting yourself up to be in a horrible spot postflop with a hand that doesn't make anything. This action sets yourself up to lose buckets on later streets. That's why its pure spew!