Would you believe that I actually had a dream about a gamemode similar to this?
The human team started at stage 3, and us bugs started at stage 1. I don't believe our stuff was protected, but if we survived 5 or 10 minutes or however long it was, us bugs were instantly boosted to S3, where we incidentally flattened their base.
I don't recommend it as a gamemode, but it struck me as a damn odd thing to have a dream about.