Having no experience with the -60, I asked Pops about it.
He said the Air Force at one point gave them M-60D(with spade grips) as door guns and he said they were the worst guns he dealt with in Vietnam. They shortly went back to .50 cals and mini-guns.
And I agree with Tuck, the idea behind the -E3 variant in appealing, or having something like the Mk-48 the SOCOM guys get.
NRA Life Member
Big Sister: "Everyone in America is fine with the .30-30, except Mack. He has to shoot that .35 because that extra point zero fives inches will matter on Bigfoot."