RE: Need help choosing! SV27 Brushless or Nitro!?..
Personally, after having electric gear and going to nitro, I would never ever even consider getting electric again.
Of course, you have different criteria for selection. For starters, nitro is powerfull and there isn't the worry of recharging batteries etc etc. Also, the sound, the smell and the smoke trail all make it that much better.
At the same time though nitro stalls, and that's fine in a car but with a boat you can't really just walk on water. You mentioned $90 in batteries etc for the brushelss version (I don't know how much they all cost) but I guess you can kind of use $90 if you buy the nitro boat to buy a retrieval boat.
Additionally think where you can run the boat. You mentioned no gas allowed in the place you wanna use it at?