Basically if you have a N/A setup, or a mild build up, you don't need an MSD.
I am hooking mine up tomorrow, on my mild, n/a, 5.0...but I have my reasons. I want a hard rev limiter, which I will set at 6k...and I will be adding a power adder shortly, I just don't know which one.
If you want a cheaper alternative, I do have a ProComp 6AL (imitation MSD 6AL) that has never been used but has been opened. I bought it to save a few bucks ($140 for the ProComp vs $200 for the MSD), but the other day I was getting it ready to install and I heard a rattle from inside. So I popped the bottom cover off and found that one of the heatsinks was not fastened. There are two of them that are screwed to the case itself, and one of them didn't have the screw holding it down..the screw was loose. I decided to not put it in my car and will be putting it on eBay for $50 + shipping as soon as I get a picture.