Correct, the comparisons are on a PC and I'm pretty comfortable saying JRMC17 is the best option for PC.  
I don't have a MAC.  I've read a lot of good things about pure music (and other players on MAC), but haven't tried them.  One day I'll get a MAC alongside to compare.  If pure music was available for PC I would definitely give it a go plugged into itunes, because the itunes organisational stuff & interface is marginally better than JRMC17, but the sound isn't as good on PC.  I actually keep itunes around to do most of the organisational stuff (but mp3tag for artwork).
Typing this I just realised that I use 4 different programs to listen to and manage my music, bugger.  I guess it makes sense, we can't expect any one company/player to be the best at everything.