I got impatient and called...
The cheapest model, H1 was the original version they came out with. The H2 is newer and heats up in about 1/2 the time. The H3 is identical to the H2 except it is not as wide. You can trim the length of the pad but you cannot trim the width. I spoke with the Tech Support guy and he said for the Recaro Trend seats the H3 is probably best because of the width.
I also asked which is better, the Innovative Heat or the H series. I was told the Innovative Heat series is a little more budget minded and not as durable.
Might have to try these out... the problem is that I cannot find much competition in this market so it is tough to really gauge who is better. Searching for 'heated seats' or 'seat heaters' results in about 5-6 different web pages which all sell the same products....
This place ships from California, Washington, or Vancouver depending on inventory in each warehouse.
Other aftermark seat heaters:
http://www.katzkin.com/
http://www.rostra.com/
http://www.sportsimportsltd.com/heatelcarsea.html