Throwing my hands up on this ignition!
I have a 426 SB and the stock ignition ran fine, then I switched to the chrome box and also ran fine. Currently I run it out of the Edelbrock proflo 4 ECU because I installed they MPFI system. When installing these things besides following the instructions and making sure everything else is okay,m you need to make sure the coil used with the ignition box is compatible, they usually have a list of the appropiate coils to be used with the CD box in the instructions manual.
As an enthusiast Im looking to improve that and did a lot of research a few weeks ago. My choices were ijntellitronix that has a lifetime warranty and intelligent an protection system because the MSD, summit and other brands have only 1 year or 2 max. My second choice was the holley EFI CD ignition box because it specially made for the EFI ECU (sniper) and does not have other functions I wont use.
I ended up buying the later because intellitronix took a few days to answer a question I had on their blue box, but I would have bought the intellitronix otherwise.