I find that flying Maarek in the advanced you generally pair him with:
Push the Limit
Mk 2 engines
Title
Advanced Targeting Computer
That leaves him at 32 points and you are going to be using his ability quite often once you punch through those shields. You are also going to be stressed, a lot.
However the Defender, with X7 and VI, has the same action economy and just makes use of his ability when it happens, doesn't try to force it and is PS9. That is serious Imperial quality right there.
In a straight up fight between the two, Defender would win I reckon.
Also, this may just be my experience but when you absolutely need that crit to come through. . . it does.