What I have seen so far is mostly the same issues Rock Doctor has mentioned. The HD bearings seem to be better for running tracks since they will handle a heavier side load due to the heavy duty flange. Overall they are an 'OK' bearing but nothing revolutionary. I really like the aluminum flange with double seals on the old bearings. You just can't protect a bearing much better than that. Argo should have built on that design and just made it tougher. If the new HD bearing fit tighter in the flange and had a greaseable oil seal over it, I think that would be the most durable bearing.
Everybody dies, but not everybody lives.