I've had my eyes out for an ST500 or ST600 to check out ever since I got this '86 SR500 2½ years ago.
Mid-ish 80s Cdale?
Normally I only take it on shorter rides, and I originally only hopped on to ride it to dial-in for resale, but what ended up happening is I really, genuinely enjoy that ride more than my words can express. I thought it looked a little goofy with the bulbous tubing and whatnot, but I really don't care at this point.
I'd ultimately like something a little more relaxed geometry, so the ST bikes seem a bit more interesting. Sadly, I've only seen mid-late 80s Criteriums and more SRs for sale during 2018-2019 and at bargain-barrel pricing ($180-300 range) but none of them are ever my size. I doubt I'd find the Criterium as comfortable.
Anyway, good luck, and my whole point for posting this is, you may actually find an SR equally enjoyable, if you haven't already given one a shot. Unless there's something I missed above as far as equipment/provisions you'll need which aren't on the SR bikes.