Are there any situations where the Bluehawk is better than the Sheller? The Sheller has 2 less speed, a bit less HP, and poor turning. For that it gets 70% more range and splash damage that instagibs every bot and every t1 unit except Infernos. Their time to hit a target is pretty equal and their cost is the same. I guess Bluehawks are better at kiting, but I don't think that's worth losing all that range and splash. I'd say they'd be pretty even if the Bluehawk had similar range.
sniper bot can't shoot over walls. bluehawks are pretty good at wasting commanders a little too close to the edge of their base, but to be honest they should be also able to shoot orbital.