I have one of each now 525 EFI and a carb blower enigine. The EFI is real nice at startup and is easy on gas. However they can be a pain the rear when a sensor fails. I like both however. Carbs are bulletproof and make a lot of power but a little rougher at idle when cold and will use a little more gas. MUCH cheaper to do a carb setup.
Right now I am chasing down a EFI problem on one engine with a buzzer going off all the time. Twice they can not find the issue when hooked up to the computer.
In summary EFI is really nice when it works (all cars have it)and carbs are real simple and make just as much if not more power.