Given your price range, I'd get the Colt and wait a little bit to buy a CMMG .22lr conversion. If you really feel like you need the .22lr capability now, go with a S&W M&P15 and get the conversion.
There's a little cash benefit in getting a lower tier AR, and given the correct choice and careful inspection & maintenance, it's a viable route to go for a low volume shooter. If you're not going to classes quarterly, training weekly to monthly and shooting competitions, you can make one work just fine.
Still, there's a lot to be said for peace of mind. Buying a Colt, BCM, Daniel Defense, etc. is paying a little more for a significantly better quality rifle. What price should that peace of mind cost?

