On the snowballing thing, it seems to really depend on the map. They're definitely not balanced properly(the main objectives I mean). Like when you do the skeleton golem map, even a max golem is still fairly shit, you know which lane it's coming on, where it spawns, in how long and it's just an AI that doesn't defend itself and just truck on, so basically a big siege unit. It's easy to mount up a defense and successfully push back your opponent and if they got too greedy and dove in the base you probably get your advantage back, plus if they 5man with the golem, even your 0 golem is gonna get a tower or some shit, giving you something to even out what the opponent will get, if they splitpush you can kill it fast with 2people and delay their push with 3, you'll lose a bit of shit on both lanes but not much on either.
On the other hand, the map with the pirates you're pretty much fucked if you can't 5vs5 and win, because all they have to do is spam the pirate canon and there is no counter, your buildings just take insane damage over and over without the enemy team even having to actively push, all they have to do is hold the middle(which is easier than pushing into an enemy base, no tower/farther from spawn).
The map with the curse is like pants on retarded, if you coordinate having mercenaries in one lane and pushing the other when you get the curse, you can finish the game in one push without having any advantage before that if you do win the one teamfight. Like I've seen a game end in something like 10mins because they slaughtered the enemy team during the first curse push and just pushed straight to the base in one go. That's just dumb as shit and that's the map with the highest potential for snowball(but also arguably highest potential for comeback if you can get the curse yourself).
The dragon map I've found was the best, as long as everyone understands how the map works(so they don't let you get a dragon at 5mins for free). It gives a tangible advantage but it's a counterable one(you can either prevent them from clicking mid or capping one of the 2 spots) and even when it pops it's not the end of the game, but gives a fair advantage to the pushing team(but since it replaces a player, it's not like a huge advantage and it can't be used for splitpushing as well as the mercs or the golem).
The game itself looks fun but like it'd be boring quickly, and if they release heroes at a blizzard pace, then I don't know how much retention they'll get. It's F2P though so whatever I guess.