I've been going to Sig for some time now, (first class was 2001.) The staff has changed but the current instructors are outstanding. I highly recommend their programs. Also if your in the market for a new firearm the student discount is substantial. The only problem may be ammunition. Most of the courses I took required frangible. If you don't have frangible they can provide it.
I can't give you advice on levels. I've always attend the LEO classes. No experience with the civilian side but I know the instructors are the same for both.