Just wanted to update everyone. I received the outboard power supply and strobe disabler this week and did the upgrade last night. Sound report? Definitely an improvement and noticeable change. It's difficult for me to describe specifics let alone use the poetry that typically accompanies these type of tonal improvements.
I'll say this -- *much* quieter and lower noise floor. Totally worth it.
I did the upgrades over several years:
+ Tone arm rewire, RCA jacks, cotton in tonearm for stabilization
+ DC-1200 for voltage regulation (prep for outboard power supply), TD-1200 tone arm dampening, Isonoe feet
+ SX-1200 Strobe, outboard PS.
Overall I think the tonearm wire was probably best bang for buck and most impactful to sound quality. It was also the biggest PITA... but I'd do it all again.
If I do move on from the 1200, I'd probably look for a platform that starts at $2k-$3k. I'm not planning on doing anything atm - the 1200G / 1200GR looks interesting - so maybe in the future. But at least for now, I'm 100% satisfied with the whole experience of DIY style upgrades to this deck. Great experience, and totally worth it.