NEA has a very good reputation for taking care of their customers. If something isn't working, they make it right and don't leave anyone hanging.
As for swapping internal parts from my orignal OEM lower, I already told Jeff that most of us 'hardcore' Swiss Arms/SIG fans would much prefer to keep our original lowers untouched and would be willing to pay extra for either a complete NEA lower or stripped lower and LPK to complete our own.
If you're willing to spend $3500 on a gopher gun, and another $500-$1000 for factory/OEM magazines, most Swiss Arms owners aren't afraid of spending an extra couple hundred for the convenience of simply swapping one lower for another.
In fact, a lot of us own more than one Swiss Arms rifle, so having one complete NEA lower that I could switch between non-restricted Blue Special/Classic Green, along with restricted Carbine and CQB is attractive to me. Spending $30.00 per AR mag is also a lot more attractive than dropping $100 for a single OEM mag.
As a civilian, I actually really like the Swiss Arms mag design. It is certainly robust enough for my needs and the ability to snap several together is convenient. However, I don't drop them on rough concrete floors or rocky gun ranges. That is where PMAGS would really shine. Having the ability to use 10 round LAR mags in target practice or hunting praire dogs, etc... is another reason why the complete lower is attractive to me. Saves on the hassle of loading mags.