Should we see a difference between a regular filter set and a filter kit that is "meant for HD"? I have set of tiffens/hoyas that came recommended for the xlh1 with BH, and am looking around different filter kits and see a few kits that are meant for HD.. Is there a difference?

I would think that the best way to determine whether your filters work on your HD, would be to check to see if there is some form of cut off (like some lens shades do at the wide angle setting on your lens), in the finished product.

Off hand, I would not think that you would have much of a problem unless it is a polarizing filter. And, even there, I suspect that you will be O.K. (Some polarizer's can distribute color artifacts in the image).

As you are dealing with a different aspect ratio from SD, I strongly suggest a number of tests.