Maybe I over-read it, but you didn't include the Black Knight in your analysis of the stats.
Black Knights are my favoured heavy cavalry. They have superior protection, HP and strength. Their weakness is their slow speed, but in combination with the overall slow Ulm army, it doesn't usually show. MR is an issue, and possibly low defense. They, however, do have the first-strike of the lance. Gold costs are the lowest of all heavy cavalry, but like all Ulm troops they need a lot of resources. Compared to (esp.) Van or Tien, this is a major drawback if you are in an area without many high-res provinces. The difference to Man and Marignon is negligible as the difference in gold is larger.
That said, I have worse experiences with all kinds of heavy cavalry than I had with Black Knights. Man heavy cavalry and Marignon specifically. I typically use a small group of Knights for expansion in the beginning, and while I always loose some with Man or Marignon, I have yet to loose Black Knights during that phase. Then again, that may be just the "Ulm heavy armor" factor against Independents.
[ April 21, 2004, 15:48: Message edited by: reverend ]