This is my first Imperial list. Any ideas for modifying/flying it?

Rexler Brath-Tie Defender (92)

-Advanced Sensors

-Ion Missiles

Darth Vader-Tie Advanced (80)

-Sense

-Shield Upgrade

Black Squadron Ace

-Elusive

200 total points

This is a pretty thing list, but I wanted to keep Vader and a defender in the list. Should I put a more powerful force power on Vader an use a generic pilot for the defender? Should I try to put more upgrades on one ship or the other? Thanks!