I suspect that a smaller, faster, cheaper, more agile transport would see a lot of use. Especially if it's before the gal in the cert tree.
If you're going to use an existing vehicle I'd pick the Liberator. It was already part of the air support cert in PS1, so it would make sense in the same cert tree as the gal. It has enough armor to get in and out of a base, but not enough to make sitting there under fire feasible. Just make the bomb bay modular and let it switch out for a troop carry module with some mounted weapons. Personally I'd like to see it with a gunship module too, since they apparently abandoned the 2 man reaver, but that's a different thread.
Alternatively you could re-invent the phantasm. Visual stealth seems to be out of favor, but maybe an appropriate sensor stealth and ewar package could replace it.