You can view my personal experience with them--in all its excruciating detail--here:
http://www.talkbass.com/forum/showthread.php?t=158802
Short version: Good product, sub-standard service in my case. And when I finally got my neck it required some extra work that I opted to do myself rather than send it back to Moses, because I had already waited so long to get it.
Again, you can read all the details in the thread above. This is only
my experience, mind you, and others have had great experiences with Moses.
Tonally, I liked the neck fairly well (on my bass it sounded very maple-like) but, ultimately, not enough to stick with it. I've since gone back to the original wood neck on my old Frankenbass. Just something I personally liked about the feel and sound a little better.
I was originally interested in the graphite necks for the durability of their fretless fingerboards. In this area I believe they excell like nothing else I've ever played. Other than that I just wasn't as into the graphite as I had hoped to be. But then, of course, business is still going great for Moses, because there are plenty of people who disagree with me.
Hope this info helps you in your decision.
Matt