Something like that would be a lot easier to manage.

Something like 8.0 or 8.5 would have very little difference; I suppose an 8.5 would be a "somewhat great upload", but I'm not sure. Ratings such as 8.2-8.3 or 8.7-8.8 might as well be the same for uploads. I don't think you can really pinpoint ratings so accurately for jj2 uploads. It's mostly opinion based anyway.

I actually do have an idea of what kind of upload deserves a 10: It has to be all-versatile for the purpose of the upload. Please consider the logic brought up in this topic. I suppose a "Very Great" CTF level would work exceptionally well in all game sizes, cater exceptionally well to all aspects that constitute CTF such as RTSing, defense etc, and, of course, can not be overcome by "virtue". "Very Great" Tilesets could have something along the lines of "Photorealistic graphics that don't look out of place in JJ2's style". They, of course, have to be all-versatile as well, with things like usability and no room to enhance.

Whichever the case, I didn't take opinions into account, so I'm not saying what I've stated above is absolute. I tend to take a "playground philosophy" approach to level design. Basically, the chosen theme caters to aspects such as the gameplay, eyecandy, music etc, and the players decide if they want to play in that "setting" (I even choose themes that fit specifically into JJ2. Golem Landscapes, for example, fits because it's a fictional creature, and also because JJ2 has been about comically "twisting" popular culture themes).