Firstly, as computers and arrangers get more and more integrated, I would try a setup where your arranger is in front of your computer monitor, with the mouse and keyboard on a slide out tray below it. Plenty of inexpensive computer workstands with that form factor.

Now, it's a LOT more convenient to record, or sequence, or manage memory backups. I still refuse to sequence on an arranger, having got used to how much more powerful a computer is for those tasks, not to mention a nice big display instead of a tiny cramped screen. USB makes it a snap to transfer work on sequences or styles to the arranger.

An H4 is a really good location recording tool. but it doesn't hold a candle to what you can do with a computer. I mean, face it, even after you've recorded your keyboard, you need to master and compress your results, and how about an overdub or two....?

You can use the H4 as a USB front-end for your computer if you don't have a decent sound card, as well. Just get your arranger and your computer together, and a world of possibilities opens up...