I have an ACS mat in my Columbus. I've used one for several years now and can recommend it. I liked it so much that I talked with the company in Germany that makes it to try to figure out a way to bring it in cheaper to the states. There are a lot of applications, the RTT market is very small, but it is a very expensive product and shipping is quite high as it is really all air. I think if there is enough interest we can talk Mike into bringing in full rolls of the stuff and then he can cut to size and the price will be a little lower.
The advantages of the ACS mat over some of the other products is that it is very light and has a nice feel. My wife took a nap on the mat only and thought it was very comfortable by itself. It adds a slight cushion to the mattress and lessens the feeling that the mattress "bottoms" out in low temperatures. It does help air the mattress out, it's main consideration, and keeps the mattress off any condensation or water that may form or enter the tent.
I can certainly understand if the price/benefit ratio isn't high enough to justify buying one. If you are just using a RTT for weekend use, it doesn't make much sense but on an extended trip, it is a very nice addition. I would think on many of the Chinese made RTT with the alloy base it would prove to be a valuable addition.
Rich