What Jim Lad said
Also, the only reason to switch from FTP to Mbox, is if you want to use Pro Tools LE.
FTP has:
Higher sample rates (up to 96kHz)
2 insert jacks
2 Balanced outputs + 4 Unbalanced outputs
A mono switch that affects playback monitoring, not just input (I'm not 100% sure if that's correct though)
An external power supply, which I'd assume takes some of the pressure of the USB cable (which is inferior to FireWire - especially when it comes to audio interfaces)
I'm sure you know all of what I listed above since you own one, but the reason I posted them was because they're all things the MBox2 doesn't have.
Mbox 2:
Max sample rate is 48kHz
No insert jack
2
unalanced outputs only.
A mono switch that only affects input monitoring, not playback
No external power supply - All the pressure is on the USB, and most people who use an MBox 2 with monitors, including myself, will tell you the monitor outputs get noisy. It's a USB problem.
I've never used a FTP, but I'm just reading that info off the website.
Stick with the FTP.