"Heavy" isn't worth the costs

[swimj]

I think the biggest benefit is that a boosted heavy has 5hp, so if your opponent wants to take it in one turn it will take either soldier+heavy, soldier+soldier+runner, heavy+runner+runner, or sniper with some similar combination. On defense, as sniper is likely not in play for your opponent (unless there is a mobi), having that heavy gives a bit of insurance on holding key spots that can only be attacked from a few angles.

It is also a really good defense for the shell, especially if you're playing on a map which has holes (sharkfood, glitch, even blitz beach for 2v2s) to place the shell where it can only be attacked from one hex if the shell is defended with a correctly placed heavy.

I definitely prefer soldiers on offense though, and would definitely take two soldiers over one heavy and one runner, despite that they are all 4 damage total.