750 Edelbrock issue

the Edelbrock 750 has been giving some hot rodders fits for many years. I had tuning problems with the carb years ago and at that time there were many posts about the various problems with idle, hesitation, rich and inconsistent A/F mixers at different rpm.
I talked at length with an Edelbrock tech and was told by design it responds poorly to engine vacuum and can be difficult to tune on some engines. Many guys obviously have good success with them but i know many who along with myself didn't!