not many people do it because it hurts resale value.
Or at least it does not add anything to the value. But if you want an old porsche with superb driveability, cold starts, etc...i would recommend EFI immediately.
Bit of a learning curve to it if you are doing it yourself. That's mainly the reason (and cost) i went for the bitz kit first. Then a couple of months ago i went further and threw out the original ignition system and went distributorless with crankwheel and upgrade microsquirt computer.
If i had to do it again, i would go full kit immediately. Couple of businesses making beautiful kits with individual throttle bodies.
Nothing beats the feeling of junking old worn out parts, never having to fear again of them failing or not working as they should. That whole lambda junk was fantastic to throw out. (got a 1981)
If you don't look at resale value, then it almost makes financial sense too, because CIS parts are getting expensive to diagnose and replace/repair. IMO. Many people here are saying CIS is superbly reliable and very easy to diagnose...i have exactly the opposite opinion. 40 year old CIS (especially the 81-83 cars) is really difficult and cumbersome to diagnose and repair as a DIY proposition and i'll bet you a large percentage of cars out there is not running properly.
again, just IMO.