I've been using GHB 24/7 for the past 2.5 years (I am currently 27). At the moment I'm on about around 100ml a day. I dose around 7ml every 1.5 hours, except when I sleep which is usually in 3 hours chunks, unless I take a benzo (which isn't often). All in all I average around 6 hours of sleep a night, give or take.
All the GHB I currently use and have used in the past, with a few exceptions, has either been made by myself or by people I know beyond a client/dealer relationship, so I can attest to its quality.
I have never really attempted to quit, but only cut down. I am not under any illusion that I would be able to quit, nor do I particularly want to, but I would very much like to lower my level of consumption, and I dream of the day when my GHB can go back to only being a weekend thing, although I don't see that happening any time soon.
I have used, and continue to use numerous supplements and nootropics in order to try and cut down and/or amplify the effects of the GHB, with varying results.
It is worth noting that at this point I barely feel anything other than the morning dose and the uncomfortable feeling I get when it feels like it's wearing off. It's the last thing I drink before I sleep and the first thing I shot to get out of bed.
Surprisingly though, overall, I am still pretty happy, although I am aware that this happiness is not built upon a respectable foundation.