I looked at the specs and ad for the monocular in question. For some reason the specs fall in between omni-1 an omni-2, not sure what that means. Also, there is technically no such thing as gen 3+, and if there was that would not be it. Normally that kind of advertising is restricted to some of the lower quality NV makers, not sure why Meyers would do that either.
If you are looking for alternatives, the actual mil-spec version of the AN/PVS-14D would be the ultimate, and in my opinion the Litton version is top of the line. ITT also makes this actual mil-spec 14, but you have to work hard to get it, and they make several variants for less money. The full mil-spec versions are very similar in price. US Night Vision sells a very nice gen 3 monocular that is nicer looking, lighter, smaller and more versatile than the Meyers device. You may want to check that out. It is called the Falcon 3000, retail is about $2300 and it has a minimum omi 2 spec tube. You can request omni 3 spec also. I don't know if I am overstepping the boundries of the forum, but will add that I can help you acquire either the Falcon, or the Litton AN/PVS-14.
As for tubes, most commercial spec tubes will either have blemishes or fall short of some of the omni-spec requirements, that is why they are commercial. Some of them fall short in many areas, that is why, whatever you buy, you need to have a satisfaction/return guarantee. I have seen some devices come through(not from Litton) with commercial tubes that were really ugly, and for what they were sold as, we could not sell them in good conscience. Others are very nice, and you would not notice any real flaws in them, usually some aspect of performance is a bit low, such as the photoresponse being just a bit low, or low sig/noise ratio or something like that. From what you stated you are looking for a 1X monocular to mount with an aimpoint or other optical sight? Therefore any comparison of Raptors or other weapons specific sights is irrelevant for now?