I run an MSD6al, coil and 2 other little MSD gadgets that control the nitrous on the LX. It's great when everything works. I've had to send the 6al back to MSD. It was way out of warranty, but they fixed it for free anyway. I think they have (or had) probs w/ them.
I wouldn't use it unless you actually needed it to control something like a nitrous application.
My SVO's ignition is stock and I've been real pleased with it in comparison to the MSD stuff.
I've run a 6AL, and TFI blaster coil with a stock distributor on the 88 coupe. It acts as an amplifier so I can be confident when I spray it. Plus I have a 2-step and some window switches for nitrous too.
I have the same of both 351 coupes where I have the billet distributor too. I made the switch from pionts and it was like night and day difference for throttle response with no other changes.
Having messed with these a bunch I can agree with stinger and say you won't see a gain. Its only worth the money if you are doing something that would be pushing the stock ignition beyond its capabilities, which I don't think I've done yet.