My question is just that: what's the best use of your ACU on water maps? Especially large ones.
On small ones, going gun seems okay, maybe even t2, as you could walk from island to island and make use of it.
On large ones, it can be quite a walk. Air dropping is of course possible, but I'd rather not rely on it because of the inherent danger. Even walking underwater can be dangerous unless you have Cybran torp com, and even then you still need air control.
Going tech seems like a waste as you could just tech up a factory you're actually going to use. With the ACU it's like... build your pgens and then wait until t3, build your t3 pgen and then wait until it's smd/arty time. You can assist with it but that's a lot to spend just to get 2 more engies worth. Lots of waiting = wasted upgrade.
RAS seems worth it but of course, that's not till mid or late game.
So... do you just use it as build power? I feel silly just leaving it in one place and having it assist things. It's not... natural... letting all that potential just sit there.