My problem is that the Kel-Tek SU-16 is a toy. Like the Mini-14 it is a weapon for weekend plinkers and Range-Rambos not for the down and the dirty. I want a weapon that will stand up to real use, not a cheap noisemaker, that is why I won't own an AR. The AK, FN, H&K/CETME/PTR, M-1, M-1A these are all real weapons designed to work under field conditions. The SIG 556, FN F2000 and the FN SCAR-L (as much as I dislike the round they fire) are built to be used in the field, even the Romanian PSl and the Yugo M76 are able to handle harsh conditions. The AR-15's, SU-16, AR-180B and the Mini-14's simply are not up to the task if you plan to use them for serious social work.
If you plan to punch paper and plink soda-cans then it doesn't matter what you use, but if you expect to get a life-saving tool you need to get the best one you can.