I'm usually happy to see manufacturers (or at least designers) on a forum, provided that they're contributing something besides "hey buy my product."

Straight sales tactics are annoying, but given how much technical misinformation and nut-job "experts" are on the web, it's nice to have someone who actually designs stuff contributing.

A "my product is great for that" response probably isn't worth it, though, if only for the inevitable flame-y grief you'll get. (I personally don't mind either way.)