Okay I have some experience with keeping them, and this is my two cents.
1) For whatever reason, mine didn't jump on the chance to eat the snails- even roughly the same size of them, they only went for them rarely. I bought five snails months ago and still have four of them today. Maybe they don't like that particular type of snail, I'll try to get others snails later.
2) they don't keep well with shrimp. I read stuff about them and shrimp being hit or miss but crustaceans are part of their natural diet and you're not going to have a shrimp population in their tank. They pick off any shrimp they find, and even if they don't directly eat the shrimp, the stress will kill them or bite wounds will.
3) they're actually pretty messy fish and need a largish size tank or they'll fight. I had 3 in a ten gallon; one died of internal parasites and another of a bite wound from a fight with another puffer. I didn't expect it, they're very calm, but all of a sudden one bit the other and wouldn't let go. The other puffed up pretty big. I was watching them and broke it up, but I think he died of infection.
4) They are NOT brackish fish, this will kill them. They're freshwater.
If you do decide on them, good luck to you, they're hardy and fun to watch but can be a nuisance.