Does anyone know if I can mix HAI & PCS dimmers? They are both UPB based (I believe HAI licenses the standard from PCS?)
Can I mix both switches with either brand's PIM?

Any preference re: quality, features etc?

Yes you can mix them. Simply automation is also a UPB product you can use. I just bought a bunch of HAI switches to install. The differences is looks and how to program. The HAI seems to be the easiest to program. Down load the UPBstart program from Homeauto.com. This is what you will be using to program the lighting.

Also check out the Home automation forum at cocoontech.com

OH BTW. don't forget to install phase couplers next to your electric panels. If you have more than one panel, add another coupler.

Good luck
Chris