My FNC was my first MG, purchased in 2011 for $6800.
At the time Colt M16s were selling for ~ $12,000, and I thought that was too much to pay for a 5.56mm MG, ha!
It's a great gun, but as mentioned above, the relative lack of spare parts, especially compared to M16s, does keep me from shooting it as much as I would otherwise.
I did have failure-to-extract problems when I first got it, which was solved by replacing the worn extractor and using the "adverse" gas setting - I was using PMC Bronze .223 at the time, which was a bit underpowered for the "regular" setting.
As others have mentioned, if you don't already have an M16, and can afford a few thousand $ more, nowadays I would go with a non-Colt RR first.
Which I finally did myself (PAWS/Oly RR pending transfer from my FFL/SOT), but seven years late, and at a price of $18,500...