I would just go for the Big Mouth Bubblers, or the Morebeer Fermonster if NothernBrewer turns you off now. I tried a few different things and I tried one of those plastic conicals (the FastFerment, not the Catalyst which has come out since).
My main problem with the plastic conicals (I don't know about the brewtech stuff) was that everything had to drain out the bottom. If it had a racking port a little up on the thing, then I might have liked it but the "only out the bottom" method didn't work well. The big problem I had was clogging, so maybe the catalyst is better for that.
After using glass for a long time, then the fast ferment for a dozen batches, I went back to Big Mouth Bubblers and have been very happy. Fairly cheap, easy to clean and work with, and hard to break. I'm sure the Fermonsters are just as good.