I do not have any experience with the 1315R but do own and am blown away by the performance of the two years earlier model Denon PMA-1080R(105w/ch). If I am not mistaken, the 1315R is the newer($850.00 in 1994) and slightly more powerful(115w/ch) version of the 1080R($650.00 in 1992). This amp is fast, controlled, and very dynamic but not harsh at all. The imaging and soundstage it produces is incredible. I bought this amp last summer for $120.00 and it by far has the best performance/price ratio of any gear I own. It will thump the 12inch woofers of my Klipsch Forte's to no end.
I have owned other Denon amps from the 80's/90's and have been very pleased with build quality, performance, and reliability.
No direct comparisons to those particular amps you mentioned but I really do enjoy the NAD stuff.
Bill