I am currently flying an Avistar, and loving it. I have had a couple issues but nothing that has kept me from flying it, and certainly nothing your instructor won't catch before the maiden flight. In case he doesn't I suggest you double check the CG, mine was kind of tail heavy on the maiden flight. Also I found that the elevator and rudder push rods were not long enough, and flexed too much. I replaced them with thicker/longer rods. I also dumped the E/Z connectors they use in favor of "Z" bends.

The other "mod" I did to mine was epoxy in the tail feathers. I noticed that the horizontal stabilizer would wiggle a little bit. I tried to tighten it down using the bolts/nuts from the rudder, but I nearly broke my fuselage. I did fly it a couple times before I did this so it probably won't be an issue for your maiden. However if you have enough time I would certainly do this.

The next thing I am looking into is getting a better roll rate. I was going to test sealing the hinge gaps this week, but I didn't get to fly my plane. If I get out on Sunday I will test it then.

Ultimately the Avistar is a great plane, you will certainly have good fun with it. Definitely let us know how the maiden goes.