Looks good Mark!
You took a realistic model for a start, those are hard, our eyes are experts with those guys.
Do you have 0 slope on the first and last frame, there seems to be a break in the cycle.
Is he walking along a path, or just cycling the action?, since there are no shadows or other reference
object, it's hard to tell. Anyway, I think it is nice to try on a path, this way it is easy to try a cycle at different speeds.
We build cycles with 24 frames most of the time, but everything is not happening in 1 second.
I think with this action, he could move faster since he seems to be putting some effort with his arms forward
and head rotating. Our forearms don't go very far in a relaxed walk.
I wonder, since you have a rig handling BVH, is it possible from there to bake a cycle, get rid of the Bvh link,
clean it up, match the first and last frame match and create a cycling walk action from there?
I am very interested in BVH, but had very poor success with linking the skeleton.