Bruce Lee swears by the stuff. He said he hasn't lost any more hair since he started it, and I think he's been on it for a pretty good while now, perhaps 2-3 yrs.
As for Revivogen, I've been on it for four months now, and I can definintely say my hair hasn't gotten any thinner since I started it. If anything, it seems just a bit thicker, but it's so hard to say for sure (I'm sure all of you can relate). I have started to shed a bit more in the shower, but that could be due to the Nizoral I started three months back.
Personally, I am just a bit skeptical of Crinagen because it contains no alchohol. While I don't claim to understand how delivery vehicles work, I really wonder how the fatty acids can get to the follicle when there's no alchohol to carry them there. I could be missing something obvious here, and I'm not a doctor, but for now at least, that is one of the reason I decided to go with Revivogen rather than Crinagen.
I'm sure Bruce Lee and Bryan could provide much more insightful information on the topic, but that's my two cents, for what it's worth.