I own a SONY minidisc player and I like it. Much, much cheaper than an Ipod. On $2 a blank minidisc you can save up to 5 hrs of music (of course depends on bitrate saved on that disc). A minidisc can be rewritten many times. They now have "G-shock" protection so you can run with them. Some have said they found skips when running, but I have not. Its got a longer buffer now. They are small, but do have moveable parts (not like solid state Ipods) and I should work for SONY. Also, my model does reproduce nice bass sounds and has a good range of volume levels (and my model is 2 yrs old, wonder what they are like now). Long battery lives... my model has a proprietary battery that came with the player (sqaure cross section) plus a battery attachment where u place a AA battery to increase playing time. I read Ipod batteries start dimishing after a year of solid use to a point where they die and need to be replaced (and the procedures I have seen to replace batteries are not easy).
Minidisc Community Mobile News:
http://www.minidisc.org/MobileMDNews.html