One thing that I think is important with a Xizor list is approach. I guess I play a lot of different lists and most of them have more than 3 ships in the list. So, the first pass can be pretty brutal. If you take Xizor with 5 Z-95's, I can see it not being a problem. If you go with fewer ships, the few games I've had see those ships blown up fast. How do people approach the enemy with a Xizor list to avoid a nasty first pass that sees their ships dead?
It's got me thinking of dropping my Y-wing with Ion Turret for more Z's.
If you have a few bulky ships, like Y-wings, you should be OK for the first pass. At least, Prince Xizor will be OK. Xizor likes beefy escorts; Pirates and thugs do pretty well in that role.
If Xizor isn't getting shot, I'd put him in the front of the formation. That way he'll have better shots at the enemy, comparatively, and he can still pass damage to his buddies.
If you're running 3 fragile ships, then I'd stick with the same sort of tactics that interceptor lists use. Avoid the joust, try to engage on the flanks of your enemy's formation. And try to make them maneuver in a way that disrupts their formation (if they have one). If you're facing turreted ships, get out of their front arcs so autothrusters can kick in reliably.