I have had a MSD 6A in my Barracuda with a Blaster SS coil since early 2005 and have put over 35,000 miles on it. It has been flawless.
Can't say that it has made any real difference in perfromance but it certainly makes the car start faster. It's running with in a 1/2 revolution.
As far as technology goes MSD makes both analog and digital systems. Mallory, Jacobs and Accel are all part of Prestolite so I would think that there products will be very close in design and reliability.
As far as whether MSD is less reliable than any of the other brands I can't say for sure but: MSD probally sells 10 or more systems for everyone of the other brands. Just by the fact that they have at least an order of magnitude more systems out there they are going to have many more failures even if the failure rate is much better.
For example, assuming 10:1 in sales: lets say MSD has a 5% failure rate and Jacobs/Mallory/Accel a 10% failure rate, that makes MSD twice as good. Lets say MSD has sold 1000 units and Jacobs/Mallory/Accel 100 units (10:1 ratio on sales) there will be 50 MSD failures to 10 Jacobs/Mallory/Accel failures. Now which one are you more likely to hear about? The one that has 5 times more failures.
I believe that anyone of those brands are very good and will provide years of good service. I just wanted to make a point that you need to consider the total population, you will always hear more negative about the company that dominates the market compared to one that has a fraction of the market but that is not an indicator of the probability of you having a problem.