Playtime is just a product of how big a hard drive you have and doesn't factor into the features of one player over another. As long as you know the different hard drive configurations available and what the maximum HD size is, that's all that matters.
I can encode everything at 32kbit and have many more hours of play time than someone with more storage with files at 256kbit.
For that reason I left useless non-stats like "playtime" out of my matrix.
Since there are a lot of new people online now:
www.mypocket.com/mobilematrix/index.php
I'll soon be changing the prices of the empeg to reflect after-market resale values (which will most definitely be higher than the current clearance prices)
Bruno