Red LAvbel, you did not say what bike this is for. Edit: Missed the bike in the title...DOH! Tim's warning is correct. MikesXS are 36 spoke rims. Edit2: The 75 CB400f used 36 spoke rims, BTW.
Shouldered rims are slightly stronger, the H cross section adds rigidity to the hoop. Many off road bikes use them for this reason. However, the shoulders do collect more dirt, water, etc....A little harder to clean. I have the Shouldered ones on my CB360, and the dirt isn't that hard to deal with. My bike handles better with these rims, I believe because of the rigidity, but I can;t be all that sure as the new spokes, proper tightening and truing may of contributed to the improvement. I had some broken spokes before I upgraded. However, I owned the bike since it was a year old, and it never handled as well as it does now. I believe the stiffer rims made a difference in responsiveness. No other significant suspension changes were made, so I feel comfortable feeling the rims, both in being lighter than stock, and being a little stiffer helped.