There are some good points in this thread and I wanted to respond to a few. My name is Matt and I'm the guy selling these kits on ebay for the past few years.
The 3M adhesive tape is inadequate to hold cladding onto the factory panels. We recommend using an adhesion promoter on the factory panels, followed by a panel adhesive. Panel adhesive will ensure that the panels never come off, which is the whole point.
It would be great if a company could produce a direct replacement for the factory panels and sell it for $1,000 painted. Unfortunately, that is wildly unrealistic. I've done some rough math on this subject, and nobody could produce these parts at a price that would compete with GM's factory Cadillac pieces. I can expound if anybody cares to hear the reasoning, but the molds would cost around $150,000 and there is not a huge demand for this stuff. It's awfully expensive to amortize a 150k investment over a few pieces a month.
The overlay fits very tightly to the factory cladding. In fact, after the kit is installed it's very difficult to tell that an overlay is installed. I would be amazed if anybody ever noticed.
As noted, the overlay fits all years of Avalanches except for the tailgate piece. That piece can be modified to fit the 06 and older trucks or you can trim it to fit a Putco chrome cover.
Finally, people have asked about buying the kit painted. In my experience, it's far better for the consumer to have the kit painted locally. One main reason is that all paint fades, and the only way to match existing paint is to have the vehicle present when painting the kit. Another reason is that we sell the kit at a price where you can buy it, have your local shop paint it and install it professionally, and still have less money invested than buying a pre-painted kit. Painted kits can be scratched in shipping, or they can be scratched during installation. If a customer tells me that a kit was scratched in the box, and I believe that it wasn't, what do I do?
Anyway, I hope I answered some of your questions. I've been reading the AV boards for a couple years but couldn't get an account approved for some reason.
Thanks, Matt