Thats not the first time I've heard a 240 referred to as a full-auto or beltfed sniper rifle. Great gun - wish I could afford one. And you're right, the M2 is at the top of the heap. Nothing like a 50. Closest I'll be able to come to an M2 is a TNW semiauto M2HB, but lately I'm kind of thinking an M82A1 may be a better purchase or me.
Oddly enough I like the look of the standard '60 the most, though thats the earliest type and supposedly the one with the most problems. The E3's and E4's are cool and have less issues with receiver and trunion wear, but I'm a sucker for barrel length and velocity.