Why not think of getting an ST3 to supplement your air cooler. I would imagine dealers would cut a better deal on them than on an ST4, but you would get that kind of snazzy 3 valve 1000 engine. I rode one around here (in bicycling togs, which turned a few heads
) and it felt both flexible and fast. Maintanence should be cheaper as well. Shocks and stuff can come later, but everything is much more modern than what you have now.
Anyway, after getting my ST4, I have a similar problem with my 750SS....what do I do with it (space is at a premium in Japan). Hate to part with it though.