@Painkiller: Low framerate? hm not sure. But as I said there was some lag. So it might have been the low ping that made it seem like burst shots. But I switched all visual effects on (hdr, antialiasing etc.) so maybe that affect the framerate. Gonna play with low visual effects the next time.

Another suggestion: Instead of holding breath you could also reduce the "breathing-amplitude" while ducking. That way a sniper could duck to increase accuracy but would not gain too much advantage (still breath "noise") and decreased mobility because of ducking.

edit:
About the perspective: I would try a first-person view. If your code is well organized it should not be too hard to roll-back to 3rd person if 1st person fails or feels bad. But as I don't really like the current 3rd-person camera view implementation I would try a first person version. maybe add an option to switch it in a test-version. So the user can try out both and give his opinion about it and compare thoses views better.

edit #2: I (of course) agree with the_clown and 3run. The final game should include only one view and its a basic design decision which one that may be. Nevertheless having a test-version with both might be a good idea to compare your idea/implementation of both views and see which works better.