I just got the 60GB Nomad Zen Xtra and love it. I was able to take my 245GB worth of APE file music (700+ albums) and convert it to Standard High VBR MP3 files and fit the whole shebange on the Nomad. The MC9 Nomad plug worked very well in downloading all of these files (took a couple of hours) and now I have a protable version of my home system.
I am not sure what you mean by "2 PCs in a flightcase", but this appears to be the highest capacity player in the smallest package for reasonable cost. Creative players are also reputed to have some of the best sound of any MP3 on the market. IPOD is smaller but more expensive and lower capacity. If you want to step up to video capabilities as mentioned above, you are definitely going to go up in price and size.
As for does it have track numbers, no it doesn't but I don't see the need for that in a portable player. No this player does not have anywhere near the sorting capabilities of MC9, but you can only display so much info on a 2" by 1 1/4" screen. You can sort by artist, album, genre, track name, and create playlists.