I have an 08 X-15 with I believe the same tower and living in Phoenix get to fully test the bimini's coverage capability. If it didn't have adequate coverage, I think I would have already caused the death of several people here over the past few summers.
The MC stock bimini coverage is adequate, but not great. I wish it extended maybe 1 foot further forward in front of the driver and maybe a foot and a half further back as the stock bimini uses the tower as the rear brace. It is pretty easy to get up and down and stores tightly around the tower, so during the winter or if I go early in the morning when a bimini is useless or undesirable, it stays out of the way and doesn't interfere with anything. Even when it is 115F here I have never had people fighting for spots in the shade, so that tells me the coverage must be ok. I'm sure I would be more sensitive about coverage and shade if we more often had more than one or two small kids on board.
I've seen a few people who had custom made biminis that looked a little larger than the stock MC. I haven't been on their boats to check them out, but they obviously exist. If you did go for a custom bimini to get one larger than the MC version, be careful and pay a ton of attention to function - stuff like ease of operation, how it interacts with the wakeboard rope, and even if it changes how the tower folds up.
I've not been on a boat with a Z5 other than in a showroom. They look like they'd be great, but I've also heard they are a few thousand bucks. I'd love one, but my MC bimini does enough of what I need it to do. I used to want one more for the storage capacity than the coverage, but that itch has left me and I rarely have more wakeboard than I can fit on my racks and the ski locker.
The MC biminis are really common, so you should have no problems seeing one up close. Z5s are a little more rare. If you can, try to get on boats with either of these and see for yourself before you purchase.
Hope this helps a little.