My .02...
I've been shot by Lobo with his MK11 and it seems to be pretty accurate. It is not as sexy looking as a longer, bolt action rifle such as the m24 or m40a1. It is shorter, which makes it easier to crawl around with.
I wouldn't rely on your rifle too much. In the sniper role fieldcraft, cammo and evasion plays a larger role. If you run around like and idiot you're going to get shot regardless.....
I agree whole heartedly about the MK1. I also have been shot with it... @ 225ft + (uh and he was using .36). The weapon is very accurate. However a "sniper" using this weapon needs to be a very good judge of distance as well. I have already sen a "Semi" serious injury come from the pistol version of the MK1 (a bb lodged in the eyebrow of another player by a player using the pistol version and had no concern for distance, and yes they were both wearing eye protection standard safety glasses, guess that's another argument for goggles.).
As a matter of fact it was the same .36 that Reaver gave Lobo to try at one of the games.
The only problems I have seen with the MK1 is in it's functions. The trigger mechanism has to be "broke in" or it doesn't always reset. Another problem that appears with time is that the mags expand and become real tight in the well. This causes you to have to basicly "tap" them back into shape with a hammer. Also the gun when in extremem heat or cold temp will not consistently(?) fire. By that I mean that each pull of the trigger will not mean the weapon will fire.
I have actually worked on Lobo's MK1 and have seen this happen at several games. Although it is simple enough to get it working again, it is stoill a real pain.
(and this is from experience)