I picked up an IMP Meer this last week and it smokes cooler, drier and cleaner than any briar pipe I own. It's simple to compare the last two elements by counting the number of pipe cleaners I've used after smoking. With the meer it's always 1, whereas I'm usually in the neighborhood of 3-5 with a quality briar.
As to taste and flavor development, the flavors from the tobacco are the same it's just the backdrop that changes. This had a more profound impact than I expected. I hadn't realized how much briar (including cake) flavors the smoke until it was absent. Of course, the flavor stands out like a sore thumb in a new and naked bowl but with break in and a decent, but not copious cake... :idea:
Contrary to what I've read about meer, it does have it's own flavor, but it is mild. Take two glasses of water, drop a gravel stone in one and a walnut in the other and I think that gets you in the ballpark.
I can absolutely imagine a scenario in which the colorations inherent to briar add and enhance the flavor profile of a blend in a way that a meer can't match. I don't see either material as superior or inferior. However I do like the experience meerschaum provides and see myself exploring the avenue with zeal.