The M11 is a good choice but it only does a couple things,
The M16 platform can do .22lr mag and belt fed, many caliber conversions, .226 belt fed. Only for extra money.
The M11 is the way to go.
The M16 and accy. is like a toilet that never stops flushing $100 bills.
http://www.youtube.com/watch?v=G38v2IBobdA