I have had nothing but good experieinces with the m60 but have heard complaints about it from many others so I don't know. All in all its a fine gun but may be a bit more break prone than the 240. The 240 is a simpler design with less intricate parts.
I yield to your point but thats not how we ever refered to the MG's we used. When we wrote up the range cards for defensive positions m249's were always refered to as lmg's and m60's as mmg's regardless of mounting options. This was due to the different properties of each weapon system. The larger weapons were set up in areas where long range fires, be it point, AP, or grazing fire, was needed. Where the 249's were relegated to short range fire lanes and backup. The symbols for each were by caliber not whether or not one was tossed on a pintle mount or not. Thats because the ballistics of the rounds mattered, not whether or not they were supported one way or another. It's not a huge issue but thats the way I was taught and we employed the weapons systems.