You should do some searches - there is a lot of cut cover info on the forum.
To my knowledge, there is only one cut-cover solution where you can do the belt by removing just one of the pieces. One guy made a cut leaving just a sliver of cover at the top. I think he was able to remove the big lower piece with the shock in place. For certain he could change the belt with the sliver still installed.
I think I'm the only guy to do it diagonal. The advantage that I saw was that when running at the dunes I can remove the bottom half and the top piece continues to protect the primary clutch and keeps sand & pebbles from falling onto the secondary. Without jacking anything up or removing a shock bolt, I can remove the bottom piece very easily. The top piece has to be turned just right in order to get it off and it usually takes me a minute or so to figure it out each time.
The diagonal cut results in the longest seam between the two pieces, and the longer seam means there is more RTV to hold the two pieces together. I was surprised to find just how solid the two halves are joined - it feels just like an uncut cover as I work with it. Of course I don't have any experience with a vertical or horizontal cut, so maybe they are just as solid.
The downside is that most of the time I treat it like a one-piece cover most of the time when I want to mess with clutches. I don't want to cut the seal and have to re-seal it. So other than when I go to the dunes and remove the lower half to keep the belt cooler, my cut is sort of like breaking the glass window to pull the fire alarm. I can slice the RTV and get to the belt quickly if I ever have an emergency, but I don't mess with it otherwise.