ALL: DM uses the PM2 spawn system.
ALL: Weapon tiers move a little closer together (IOW, the "weak" weapons become a bit stronger, but still don't match up to the power weapons).
ALL: The "cripple effect" on the LG is removed (this is the thing that spazzes up your movement when you're being shaftlamed, especially if you're HPB). In return, LG gets a bit more "real" knockback.
ALL: RL self-damage rules are tweaked to reduce "magic" behaviour (RL only does 50% damage to you ATM, which is retarded: it lets people just whore it at point-blank range and only take half damage while the enemy takes full. If you remember, we did something similar with the GL a long while back). We reluctantly decided it still had to keep SOME magic, because otherwise RJ's become prohibitively expensive.
ALL: Ammo counts (pickups, boxes, maxes) have been tweaked a bit.
PM*: Backpacks hold slightly less ammo.
PM*: Something magic happens that makes CTF good again. :P
PM2: RL bias drops from 15 to 10.
PM2: plasma becomes "fat" (plasma is actually the same size as an MG bullet right now, despite what it looks like - this gives shots real volume).
PM2: BFG gets a wider splash (halfway between PM1 and the current PM2).