Fair enough. Then there are 2 advantages to retrofit EFI; more convenient cold starting, and automatic altitude adjustment.
But I have to disagree that proper carb tuning can't overcome problems at altitude.
I'll disagree with you, too.
EFI will outperform the pro carb tuner.
It constantly tunes the system for atmospheric conditions. Cold start and altitude are just two parameters. When climbing to 8,000+ feet the EFI doesn't need to stop and pop the hood. Continue on to 11,000 feet and cruise into snow. The EFI makes changes for the altitude and temperature as you drive. Head down the other side of the mountain and the EFI retunes the car for lower altitude and higher temperatures.
Driving on a hot day and hit a cold front and a storm? No need to pop the hood. EFI compensates automatically.
The awesome pro carb tuners will diddle with the carb when clouds block the sun. The EFI guy is sitting back relaxing or working on something other than the tune.
Under WOT conditions the carb will run with (and sometimes squeak past) EFI. However, on the road the EFI will win every time.
As for parts availability, with a proper system the only part you need to worry about is the controller itself. Everything else will be off the shelf stuff. Chances are good those bits will be around for a long time due to production volume and interchangeability. Should the computer itself die you would need to replace it but in all but a few extreme cases everything outside the computer will be good.
I still have an old Electromotive TEC II system that works fine and it's been out of production nearly 20 years. If I want to upgrade I can pop a new computer on there and reprogram.
