Well guys, there's no sense in all that worrying. I hate worrying about things too.
That's why I just shoot with my MGI QCB, and quit worrying.
Funny, but I never lose zero with mine, and I use 3 different barrels.
I just zeroed the front sight on each barrel the first time I used it.
Then it is already pre-zeroed every time I put each barrel on.
No mess, no fuss.
About the forend "not being so useful", mine is pretty useful.
I have a KAC vertical fore-grip on the bottom, and a Surefire on one of the side rails.
I have plenty of room on the other side rail to add something else, but I really see no point in hanging everything but the kitchen sink on the rails. I have room for everything I need.
What else would be put on there anyway, a laser? There's room if you want it.
For my red-dot sight, I use the cantilevered receiver mount. Works great.
As for wearing out, they have been tested for over 2 years in prototype, with alot of barrel changes, so I don't expect any trouble with that. Jeff Zimba of Small Arms Review magazine has been using his for over a year now, and likes it alot. You can read about it in Nov. when the Dec. issue comes out with a full review.
Switch the barrels for different lengths, twists, contours, and calibers, while still retaining great accuracy and zero.
What's not to like?
Price is very competitive when you consider you have to have entire extra uppers with freefloat handguards for every other barreled upper you'd need to get similar versatility.
Maybe it isn't for everyone. But, then, nothing is.
I'm keeping mine.
BTW, it's really cool to transport an entire M4 in a Zero Halliburton business attache case.