I've got the cd Mk2 version which is the latest one. I love it and use it all the time to practice. I'm sure the mp3 is good as well. I suppose it depends on how you store and listen to your music for practicing. I have ended up burning loads of cd's with songs to play along with as my music room is separate to my living room, so the mp3 would be good if I was too upgrade.
The features are very good and I particulary like the bass cut when you play along as it's too much with the original bass track playing. The tempo change is great for progressively learning harder songs. The key change saves detuning for those occasional songs. It will also do both at the same time The loop facility has come in handy. The Eq is needed to get a good tone and some of the effects (chorus especially) are ok if you don't want to plug any pedals in. It really is an all in one bit of kit for home practice, with a tuner and a metronome as well. I use it for when I'm teaching as well. and can make cd's of songs with the bass cut and slower versions for my students. It's already paid for it's self.
Go and get one, whichever one it is.
