Just a thought for GAC

That would only work in a very particular scenario.

Also part of the strategy in GAC is choosing a balanced defence and attack lineup, its absolutly fair which is more than can be said for your "first person who clears can reinforce their defence".

It also doesnt promote having larger rosters any more than it does now, guessing you aren't a late game player as when you get there you'll find you have it all anyway and only farm new stuff. 

Anyway, as it is fine, there is a benefit to going first- if I full clear (which I usually do) then there is pressure on the opponent to at least match my effort. In the event that I don't full clear then it means I've screwed up and I fully expect the L. In the current efficiency meta I couldnt care less what they do, my focus is on me clearing them as efficiently  as possible.