Some earlier NADs had a few problems. But they always sounded good. In fact, personally I like the sound better than Rotel, but that could be splitting hairs.
I have not compared the M series with Arcam but looks like they are priced to compete.
Cary has always be a notch above these I think (I would put B&K in the same as the NAD, etc.) but I really think the gap is closing. I guess it gets down to a lot of auditioning and selecting with specific speakers in mind.
Samsung PN51F8500, Emotiva UMC200, Emotiva XPA-5, Samsung BD-H5900 BluRay, Dish Hopper, Furman Elite pf-15 conditioner, Dali Ikon (Ikon6, Vokal2, OnWalls) Outlaw Audio LFM-EX subwoofer.