Im sure the Ford coil packs are plenty fine for your average A series, but there is a benefit of separate coil packs. I can't really find a good diagram of the Ford coils to see how many sets of windings they have, but regardless of that matter the coil(s) are very small and the form factor is bad for expelling heat. The 2 post GM coils should run cooler and theoretically be able to handle more dwell before damaging the coil, spark voltage should stay more consistent or just output more. I do plan on getting the car running on the cheap stock Ford coil that I already have, but when I get aftermarket coils I will probably buy the GM coils.
I do find it odd, looking at MSD/Accel coils I can't figure out which one is better... Depending on where you find the specs the turns ration, voltage, resistance all vary. Like the MSD coil resistance is lower and the turns ratio is higher, but the voltage is lower, actually lower than the Accel Ford coil. MSD GM Accel GM MSD Ford Accel Ford I don't really like the higher primary resistance of the MSD Ford coil, some of these specs are very strange, but I assume a lot of it is them trying to feed you snake oil. The only thing I trust is the resistance, inductance, and turns ratio, those should be specs you can trust buying any transformer device. The MSD GM coil seems the most efficient to me, I don't really expect 45k volts, especially at an rpm where it matters, I do know for sure that about any of these will deliver a stronger spark at rpm than my single MSD Blaster 2 coil.
The comparison that I would like to make is performance off idle between Megajolt and an old fashioned MSD box. Did you have one before you installed the Megajolt?