Roland VS840EX vs. VS880EX

[jelly]

I'm consider about both of this thing.. I think VS sirie is a cool multitrack recorder.. But for 880ex the price is double from 840ex. Which I'm asking you is it worth? I think i like the automation , I like the SCSI port that can connect to computer.. But about TSR balance line? I still confuse that how is it? Can I use the line which one head is XLR and the other is TSR? (which come out of preamp) ? Can you tell me about the bad things about both of this? Thanks a lot!