I don't know if I would sacrifice game smoothness (if it was to suffer) for more players. It's very impressive what they've accomplished so far, and playing the game at solid 60FPS with no lag and perfectly smooth controls really feels good, which is something I wish I could say about Socom or other such games that I've tried so far.
Btw, very significant improvement is that now you have three control modes to choose from: first one is the exact copy of R&C2, second is like FPS controls in third person mode (you use R1 to fire) and it's the best mode for playing online, IMO. The third is an actual FPS mode. It's also very satisfying that all the control modes have a really smooth feel to them, they nailed the right stick POV control perfectly, which is something very few dedicated FPS games ever did (and none on the PS2 from what I can rememeber)
What I'm talking about is that there's a huge difference between games that have linear POV moving velocity (bad, bad, bad) and those that accelerate the longer you push the stick. The same problem also applies to many 3rd person games, but it's not as jarring there as it is in FPS games. Just try rotating the camera in J&D (see how 'right' it feels?) and then rotate the camera in 'Pitfall: The Lost Expedition' or some other such poorly made platformer (feels somehow 'raw' and just wrong).