We finally got our hands on a Anvis-9 aka F4949. I've wanted to try one of these for a while but not as a primary goggle because of all the things I'd heard about them being very fragile. I did this overview video (below) after having them for about a week. A few days after finishing and uploading the video to You Tube, the Mrs. accidentally dropped them on our wooden deck w/ rug.
Well, all those things I heard were 100% correct. It didn't hold up to the drop. The PAS (pivot adjust shelf) cracked in half. This same damage would happen if you ran them into a door frame, tree limb, etc. After contacting several people about fixing it, it looks like it's going to cost anywhere from $250 - $700 to repair.
As much as I like them, I'd have to highly recommend against buying these especially for new users unless you get them for a killer price you can't refuse. The ball detent/plunger interface has a higher drop risk and if you drop them it can be a costly repair. If you buy them, you definitely need to budget for when this happens because the odds are it will.
The worst part is that I can't get anyone to share any info on repairing these. That's either because of ITAR (I'm skeptical) or they simply want to make money repairing it. At close to $700 or possibly higher to replace with the same shitty parts, the better option is to buy an RNVG or other housing and swap everything over.