I've been thinking about getting one for a while, and after helping my buddy get airlifted out of the forest after an otherwise innocent crash a couple weeks ago (not neck related, but still serious), it seemed stupid to wait any longer.
Got the 20% coupon from the Cyclegear flyer (that all of you probably get too), and somehow walked out the door yesterday dropping $167 total on a $225 Leatt Adventure. Don't ask me how that happened. Still, even if you don't have my wife with you and you "just" get 20% off, that's still well under $200 out the door.
Interestingly enough, I bought it for riding dirt, but realized after sizing it correctly for my EVS compression suit that it also fit my Aerostich (with a back protector) perfectly. Tested it on my commute this morning and it turns out that its fantastic for the street too. The only problem folks might have is with a bike that has significantly more forward lean than my F800GS--right now the back of my helmet is *almost* resting on the brace's "platform" if I sit back and lean over a bit. Much more forward lean and the brace would probably prevent me from tilting my head back into the correct riding position. Not a problem on a KLR, of course.
Initial build quality seems very good, and there seems to be enough adjustability for most riders. It has three spacers that change the distance between the front and back halves of the platform, and three different angles for the part that goes down your back. The higher end models have more adjustability (which may be necessary depending on your size and your gear), but I found that I can adjust from *almost* perfect fit with no gear, to near-perfect fit sitting on top of my EVS compression suit (for dirt riding) or my Aerostich Darien with a back protector (for commuting/ADVing)...AND I can still make it bigger if I need to.
Under $200 for a significant bit of otherwise-life-changing prevention seems like a no brainer to me. Consider that my $400 Sidi Vertebra Corsa and $300 A* Tech 7 boots don't do much more than keep my ankles and feet together so I hopefully don't walk funny after an unfortunate crash. My $167 neck brace works on a slightly more fundamental level--its job is to hopefully allow me to continue to walk, period.
I don't think I'll ever get on a motorcycle again without it. Paralysis, I assume, is the suck.
Go buy one. Next to a helmet, it is, IMHO, THE most important piece of gear I own.