The US Army appears to think so, the US Rangers have also been issued the FN SCAR which is also a piston gun.
I am not really sure a piston design is inherently more reliable than the direct gas impingement design but it would appear that with current technology the piston design is more reliable as tested by the US military.
For what its worth though I am not sure this is little more than an academic discussion for 99% of the posters on the board given that poor reliability in a combat situation for our firearm is not a highly likely variable that will affect our lives significantly.
