I also tried an Accel 300+ box, made no more rwhp and it burned up on me. I have used an MSD digital 6 ever since.
When Supershops was open, way back when, they had Sparky on the counter. Speedtek has one now. It's a mallory distributor and coil with a power supply and an adjustable airgap to simulate cylinder loading.
We stacked business cards between the two leads, over an inch apart btw, and the Jacobs pro street box sparked around the cards and melted the cover. It only worked for a few seconds and went poof, never worked again. The Mallory box just petered out, only made a buzzing noise.
I know this isn't exactly a scientific test but the Jacobs box did kick ass for a few seconds and burned up, never to be heard from again. The Mallory box didn't like this test but when about 75% of the cards were used it would burn right through. Most of the employees used it to light cigarettes on a daily basis to. Back then I didn't know anyone with MSD stuff so we never tested it.