If I could throw in my two-cents at this late date, I also have both: a tank in the Clergy from GT and am waiting on a Sportkilt in it for more casual wear. I also have the Black Stewart from Stillwater. I find the latter a much more visually appealing tartan and am impressed by the photos of the Washington band in it. So it has my vote for band wear!

Btw, I wore the Sportkilt Hunting tartan (their own design) to our national meeting and introduced it as the "Franciscan" tartan, due to the hues.