I am almost made up on which AR-15 I am going to get first and am looking very strongly at the Colt LE6920 with Magpul furniture. However, I am very new to the AR world so want to know what reasons there are not to get it and what I should get instead. Is this a good option? So far, the only con I can see is the carbine-length gas system. How big of a downside is this? Is there anything else I'm missing? Please note that I cannot build an AR in my current situation. Thank you!