Have no idea what the issues were with reliability; saw a few people mentioning this on one of the various analogue forums. I was unable to find one to purchase new in any event.
The Shelter vs the DL103R might be akin to a very, very good solid state Class A amp vs a quality SET tubed amplifier. The denon sounds a little "fatter" and the Shelter sounds "crisper". They are both very good; Shelter has a bit more output than the Denon but both are consideredd low output.
Denon is supposedly more difficult to marry with an arm due to its higher VTF requirement and compliance rating. I use a SME 312 which works well with both cartridges and sounds very nice.
I also have a Dynavector DV20XH but it is not as good as either of the above cartridges. I have it mounted on a Yamaha PX3 turntable which is part of the hometheatre.