Ian, my arranger is the PSR-S700. My synth is the Roland Juno-Di. I've moved away from the all in one synth workstation and now use my Juno-Di with a DAW. It's also used as a midi controller too. The Di covers A LOT of music and coupled with a DAW, it's a great composition tool.
I also use the Beat Thang Virtual for creating hip hop and other modern styles. The Di makes a great midi controller for this. Plus I still have my trusty old Roland RS-70. We're attached at the hip I guess. I think I've had that synth now for at least 10 years. Its got a broken key that's taped down, and I still use it.
Squeak, have you had a chance to play the new Casio XW-P1 Keyboard synth...it has a wicked sound, and a lot of control over that sound, and the price is pretty good as well.
I used their CZ-1 synth (got started on their CZ-101) on stage in bands, and this new XW-PI is every bit, or more, professionally done. I've sold my JP-8, so I may look into something more modest, but with lots of power (including on-board effects) too. Perhaps the Groove Synth, the XW-G1 would be more in your direction?.
Either way, these are great instruments...I had a quick chance on the XW-P1 and it's very well made, and from the few minutes I played it, it sounds very good indeed.
Ian