we looked into it quite seriously and talked to someone who fits it as our dogs have trashed our lawn. You DO need to peg it down and only the toughest one is okay for dogs as they would be able to dig through the cheaper ones, or just claw the tufts out of the really cheap ones. We got samples and its actually quite rough, It would depend on what the toddler got up to but I do remember that football stadiums went back to the real thing because of the friction burns caised by astro turf, of course this was some years ago. I would also suggest that you get samples if you go ahead as when we saw it we weren't that keen on what it looked like, also cost an arm and a leg!
The upside is that thw stuff that is okay for dogs had an open foundation so wee drains straight through but yu would need to hoase off residue, also (sorry of this is tmi) of the poo is a bit loose I would imagine that it would be hard just to pick ip and would probably need the residue hosed ff too which might not be so easy given that you would want it clean enough for the littlie to play on
hope this helps