I think the majority of that difference is due to tires. The MS has summer tires while the LX has all seasons. I'm willing to bet if both cars had the same tires on them that the distances would be close to identical.
Of course it is due to tires. Sport models have stickier rubber than base models do. All auto makers skimp on tires. The ones that came with my Fit were junk. I had an aftermarket wheel and tire picked out before I bought it.
Ill concede the point about the tires but not to the distances being identical. The distance may also be due to fact that the MS had larger diameter discs as well.
So lets says that comparison was not a good comparison.
In regards to stopping distances there is alot of variables, most important would be speed... and thats why I mentioned to use a percentage.
Give me some testing/evidence to compare with that showing disc/drums getting close stopping distances as 4-wheel discs. Im fed up doing the research.

Anyways in regards to disc/drums, based on what I felt when I test drove a civic with discs/drum (as compared to my mazda6) was that the distance felt much longer and there was more of a "diving" effect up front. Just my 2 cents.