I hope nobody will mind if I chime in on this. I realize that some here sell reflective chairs, but I feel this is very important information:
In my experience,
all reflective seating is a disaster acoustically if the seat is high enough to be behind your head. Which I assume is all of the brands and models. The main problem is comb filtering - a series of peaks and deep nulls caused by early reflections. In the case of a reflecting surface right behind your head, those reflections are very early. The result is poor imaging caused mainly by the skewed response.
For anyone interested, I tested the effects of reflective seating recently, and the results are in the last section of this page on my company's web site:
http://www.realtraps.com/rfz.htm
--Ethan