I bought a Pinnacle drysuit about 3 years ago, and have about 450 dives on it. I'd say about a third of those are while teaching, and another third tec diving. (read 'extreme use')
Overall, I am very happy with the suit. I had three suits before this one, and have dove in several others, so I felt like my decision was pretty sound. I really like the close, custom fit contour, and the features such as the bombproof zipper and low profile cuff dump can't be beat. I think it's probably the best suit out there for the price.
Overall, my only complaint (a small one) is the material. All the advertising hype aside, I think the DUI crushed neoprene will last longer, and despite their competitors claims, CF is made with a fundamentally different process than other compressed neoprene.
After about 18 months (admittedly of hard use) the material in my Concepts suit did start to 'weep' in spots, and developed small leaks in others. I have had it in to Diving Concepts about 5 times for leak repairs. Right now, it is completely dry, and I don't plan to get another suit for a while. When I do however, I will probably bow to the juggernaut that is DUI.
One thing I can advise on, is that when you do need 'tune up's' and repairs, use DUI, not DC. DC is more expensive and I have never had my suit back in less than 4 weeks. Not good when you work in the water every day. DUI's repair is actually less expensive (gasp) and their repair quality is second to none. I also had my suit back in 7 DAYS!
I have a close friend who has over 1000 dives in his DUI, so that has to speak for itself. I still don't like how baggy they are though, and the whole rock boot thing... Please. They have made available the 'cave cut', an improvement but I still think it's too frumpy.
If I could just have a Pinnacle made out of CF, my life would be complete.
Hope this helps...