Biggest downside to vintage low production bikes is finding parts. It's crazy how a really nice bike can be worth far more parted out.
I was 11 when I read about the Honda CX500 Turbo in my dad's 1981 Popular Science magazine. In 2002 I bought a 7K mile 1 owner pristine example. 22 years later I still own it and when I get too old to ride, I'll keep it just to look at it.
A year later, I also tracked down and bought the ultra rare CX650 Turbo. While they may be average off the line for a small twin due to compression, both bikes have ungodly roll on performance, even the 500 killed the 1100 Katana. 500 has lag and comes on like a beast making it quite dangerous even after you get through the learning curve. 650 has no lag at all, and it takes one hell of a modern bike to beat it from 40 to 140 mph. Both are also limited on top end due to gearing, 130 for the 500 well into the red band at 10K rpm, and the 650 (taller gearing) might squeak out 150 while trying not to float the valves. Really wish Honda gave them a 6th gear.
Plenty of technology under the skin with fail safes...if the ECU can't take over there will be another sensor. The '82 500 (actual build date '81) has sequential EFI, 3 map Denso computer (self diagnosing with LED bank on body), runs at 19.3 PSI of boost on 93 octane and has no intercooler.
'83 650 (673cc) got a drop in boost to 16.7 PSI but a bump in compression. Also a weight loss going from the 500's fiberglass fairings to thermoplastic.
Both are also push rod V-Twins (4 valves per cylinder), so I get the added bonus of rubbing that into to Harley guys after decimating them.
Once the body is off, it's like working on a cyborg. Honda had special trained mechanics that worked on them. Price was $5K in '82 and '83 and Honda supposedly sold them at a loss, they were more of a "look what we can do" bike. And a lot of the technology made it into their cars years later, which is great because a number of sensors and items like fuel pumps are compatible. The 650 can get some decent money these days, I've seen them go over $20K for extremely nice examples.
Oh, and these two bikes were designed by different teams at Honda and share next to no parts!