Full-auto makes all the difference, especially in a gun designed for (reasonably) sustained fire.
If you want an M60 to defend your home with, Rock Island Armory registered hundreds of them before the 1986 cut off date, so there are plenty of fully transferable M60s on the market.
Interesting story. Some time back when the military was replacing the M60 with the M240, I read an article about how the M60 was nothing but trouble and the M240 was far more reliable. I commented about the article to some friends in the military.
Their unanimous (and vehement) reaction was the exact opposite of the article. The M60 was "old reliable" that had saved their lives more times than they could count, and they had had nothing but trouble with the new M240s.
I don't know if it was just that they were still having to adjust to the new and different guns, or whether "reality on the ground" was far different from what the people in charge wanted to portray, but I still think about that whenever I see an article say that the M240 is an improvement over the M60.