Guys -
Thanks for all your ideas. You've given me lots of help and many good suggestions, and I appreciate it. Yes, the 001 looks very attractive, and I've considered all the Modal Electronics instruments. I think my quest has worn me out a tad, though; I've got synth research fatigue. It hasn't produced a clear direction, as I thought it would. So, I probably need to make some mental adjustments. My current set up has me quite satisfied, but I did want to add to it just one instrument with that classic old school analog sound. It's been my intention for a while to complete my set up to a relatively satisfactory degree, and to devote more energy to composing and recording. I'd like to spend much less time online and much more time on the actual instruments producing something like a finished musical product.
In terms of keyboard synths, I probably would have liked the Dominion 1 above the others, but it's not available or serviceable in the US. In terms of modules, the Hypersynth Xenophone probably came the closest, but I'm not convinced it has a tone significantly better than the DSI stuff. Nothing has really struck me clearly as being "the one," so I'll continue with this quest, but I'll take my time. Who knows - perhaps it will all end with a Prophet-6 or OB-6!