Paul,
Those Personal use Yamaha's, like the one Kramerguy mentioned, are great for giving to your daughters for a Christmas Present, but I have the distinct feeling the you are WAY beyond mere toys!
The Nord mentioned by J-H is no doubt an excellent ax, but, a whole lot more then you need, or seem to want to pay.
The MM6 is a professional synthesizer that will do what you want, is highly portable, inexpensive, and has enough features to get your creative juices flowing for many years to come.
You obviously do well with new technology, so don't get to hung up on your vintage Wurlitzer. I still love my old Farfisa Combo Compact, (that's the "Come On To Me" organ) and once thought that I'd be giggin' with it for the rest of my life, however my Yamaha SYs put that ol' transistor box to rest once and for all !
That MM6 is like having my two SYs , a real time vintage ARP or Moog, Your Wurly AND my Farfisa, all in one package!....PLUS
It has on of the best sound generating systems on the market...(Advanced Wave Memory)..same as the Yam flagships, the Motif. PLUS
You can plug it into your computer! so you get to greatly expand your home recording studio capabilities.(comes with Cu-base)
all for around six bills!
seems like a "no-brainer to me, BUT if you do happen to come across anything better, let me know, since I'm hoping to upgrade myself someday,assuming I get my accounts back up to par!
Keep on creating, and take care of all those girls. (If ya do get the MM6, you can buy them all something nice next Christmas, and they wont need one of those cheap wall-Mart keyboards.
later,
Howlin'