Huh, I would have thought that Vessery's ability would boost his efficiency much higher. I still Think Vessery with Engine Upgrade makes up for it. Palp Aces also tends to have a little wiggle room points wise, so I don't think a few percentage points of inefficiency matter that much. I suppose it denies you Inquisitor Palp Shuttle Pmega Leader Wampa, but I'm not sold on that squad. Wampa dies immediately every time.
It depends how often you get Vessery's ability to trigger (that was assuming 50% of the time), and how often the x7 evade triggers (that assumed 75% of the time). If you increase his ability triggering to 100% of the time, then his efficiency increases up to 105% (with x7/VI/EU). Tactically that number will be lower if you use an action for boost instead of focus, but that's how it is with any ace.
As a reference point, Vessery + x7/Juke @50% TL ability trigger is worth the same amount in raw dice as Vessery + x7 @ 100% ability trigger. But the latter is PS8 so synergizes better with Inquisitor, letting you get closer to that 100% number. Vessery really has to be VI'ed with Inquisitor to work at all, otherwise you're better off with Ryad.
The other option with Inquisitor + VI Vessery is the TIE/D + TB/Ion option. You lose the Engine upgrade, but get more jousting value. It makes Vessery a really obvious target though.