Hey Rev,
I don't have any experience with your particular box, but I'm not terribly fond of Mallory. Admittedly, this is mostly because when I did buy a lot of Mallory parts (15+ years ago), they were notoriously junk. I have had several customers that had newer Mallory components that failed prematurely, but not enough to honestly be able to label them as junk. The coil in our Sprint car is a Mallory, and it works, but I would still be hesitant to recommend their products.
Of course, you didn't ask me that, did you?
The increase in power gained from an ignition system upgrade depends largely on what it's replacing. If you are replacing a standard points ignition system, you should notice gains, specifically easier starting and a better top end. If you were replacing a good EEC-IV ignition system, the difference would be minimal, noticable.
IMHO, the plug wires are the single most important part of the ignition system. After all, the best ignition system in the world won't do you much good if it can't get to the plugs.
Take care,
Chris