Stormtrooper is pretty meh from my experience. I geared him up a bit when I was trying to round out an Empire squad and kind of regretted it. Maybe he gets good at really high gear tiers, I dunno, but based on your current squad that's a ways off yet anyway.
If you do swap him out - which seems like a wise move if you already have KRU in there tanking - you could go for one of the other troopers. Magmatrooper and Deathtrooper are both fairly easy farms with solid damage output, and either would get you a head start for an eventual Veers/Starck squad. Personally I would go for Magma and focus your Cantina energy on getting Kylo starred up. He becomes a really strong tank, and is essential as leader for First Order.