Sort of adding to what ohmeohmy said...
In my case, I have a Roland 2480 and a computer; linked digitally.
I use the Roland for real time multitracking and mixdown. I'm "old school" and I'm more comfortable with real faders and knobs, etc.
I use the computer for editing and loop creation (Sound Forge and ACID). Don't get me wrong... I like my 2480, but editing and loop creation are a lot easier to do on the computer.
In your case, you have multitracking capabilities on both units, so if you think about it, you have more tracks than someone like me. Perhaps you could work with that mindset?
As for linking the units, I know the 880EX has optical ins and outs, so do it digitally.
And speaking of your 880EX, I still have mine, and I use it for its effects.
Selling it just wasn't worth it. They're only going for $200 to $300 dollars nowadays, so you might be better off keeping it, or selling it to buy something for your studio or computer or both.
The bottom line here is...
1. Whatever's been working best for you is gonna work best for you. Don't let hype, marketing, or other people influence you. It's YOUR setup.
2. Having something and not using it a lot is always better than needing it and not having it. Murphy's Law clearly states that one week after you get rid of something, you'll suddenly need it.