Mark,
The general consensus among those of us that roll crimp would likely agree with your first statement about the PR product outperforming the BP product. And those that have had the chance to use both the PR model and the Lyman model would overwhelmingly side with the Lyman, I'm sure. The reason is the four (to as many as six) rollers in the Lyman head - depending if it is an early or late model.....in comparison to only two in the PR offering.....and a mere one roller in the BP offering. The more 'rollers' it has, the more the developing crimp is supported as it is turning over.
If you have a friend or acquaintance with a Lyman head, you might ask to borrow it for a test run as the difference is very apparent not only in the finished appearance but in how one can feel the crimp turn-in to the correct depth. Just be sure to give it back, as they are that nice!
Rob
