Tascam US 2400 vs FW1880

[MERC]

Can anyone tell me which of the two I would be better off with? I currently have a Delta 1010. I can't see why I would pay 1300 for an 1884 when I can get 24 channels for 300 bucks more? And why would I pay and extra $1000 just to get an extra 8 channels for the FW1880? Is the only big difference the fact that I would no longer need a sound card with the FW but I would still need it with the US 2400? Please enlighten me. This would be a big purchase by my standards so I want to make sure I make the right decision. I'm using Nuendo and I also have Pro tools but don't use it at all. Bye the way, will I be able to use the US2400 w/Protools too? Sorry so long.........