I had my Rem700 cut down to 16". My MAE moderator - the long over barrel one - came to within a 1/2" of the stock fore end.
It actually looked very good, balanced well and shot better than before the chop. I was only using it for stalking out to 250m and it worked very well. I didn't notice any loss of performance at those ranges, but it was really handy to carry and use.