2D overlay is good for games that really need it, like the war-type ones. This is kind of a run-and-gun type game.
The more suggestions I consider, the more I kind of realize that there are really two fronts of this mod: modern playability and authenticity as has been mentioned. It is true that the radar was always on for all modes if you set it; they did not put the proper code in it to be dynamic, if i can recall correctly. So, for instance, should the man with the Golden Gun have radar only? Should everyone else? One of these would add playability, but neither would be authentic.
I think it is necessary to consider the changes you have to put in to sustain 12 people killing each other than the original 4 max. Team play is confusing, and really non-existent if turning it on really just means modifying the scoreboard. One guy on my team ran up to me and unloaded three clips into my head (wouldn't be the first time i have been shot in the ol noggin), before someone someone realized what was going on and killed us both.
You guys did proper things concerning level sizes and expansion. I commend you on this.
The evolution of the game, I think, should also account for some of the changes seen in perfect dark; hunting and throwing knives were one in the same, for instance, and added playability. They had the time to make reload animations, though this would be largely aesthetic. Tell me you guys didn't think flipping the knife around wasn't cool? It could look like a reload and still work.
Think what TF2 did to improve TFC... they decided against making a direct TFC port and did not make "classic levels" but expanded and improved them. Don't make GES into TF2, but read their blogs when they talk about programming (along with L4D). It is very insightful.