I'll go straight to the feedback:

-Think this was already mentioned, but lose that armor shard ledge. Unless your intention is to piss people off. :P

-I'd try taking away the bars so that you can access the YA from both sides. Would make for more interesting fights w/ one guy coming from one side and the other from the other side.

-Not a big fan of things on crate just out of reach. Yes, I know you can ramp jump to it, but it is just annoying IMO. Also, the ceiling is in the way from landing on the 50h from the JP anyway, which is also annoying.

I've got different plans for this area anyway though...

-Hmm, not convinced about the RG area. Seems like a campers nest since you can just snipe away from behind the fence. I'm thinking maybe you should get rid of this room all together and move rail somewhere else.

-Again, not a big fan of "puny" items getting put in hard to reach places like this 50h. Maybe if it was a powerup or something. I'd just lose the perch altogether.
-Oh, and I'd consider making the fencing into glass so you can't just camp here with rail and pick the other guy off. Make it so you can see the other guy through the glass but can't do anything about it to create that suspense.

-This area is filled to the brim with stairs. I feel like its gonna be too much. I'd think about redoing the entire area and maybe opening things up a bit more so its not just a bunch of staired hallways.

-These items behind tele don't seem worth the time and effort to ignore the tele, walk behind it, and grab them.

-I'd maybe level off this area so you don't have that ramp that takes you higher but just a flat floor. Lots of ramped floors everywhere tend to make movement funky w/ Q4's physics IMO.

-Ok, here's the GL/50h area again. If you raised that ceiling quite a bit, I think this would make a nice area for YA or MH. Right now, this side of the map is empty.

-Maybe extend the ledges further along the length of the wall so you don't have to pixel jump it.

-I'm standing w/ my back to GL. This area seems too tight what with the big gaping hole in the floor along with its 32 unit trim. Give me more space to roam free and not get caught on trim.
General Suggestions:
-Think this was already mentioned, but instead of rampclipping entire stairways, just create ramped trim on the sides and don't clip the stairs at all. This will create a better visual cue for the player to know he can ramp off the trim.
-Item placement: I'd maybe try removing RG room, putting RG in MH spot, MH in YA spot, and YA in GL spot. Optionally, you could add an additional YA in corner of the map where the MH currently resides if things need balancing.