The reason to get the Diamondback is the ability to mount stuff to it and maximum security. Think of it as a platform to build off of as much as anything. It’s a bit much for just a cover.
I've been happy with the x4s. Because of the height of the Gladiator bed is noticeable shorter than other trucks I'm used to, I find myself rolling the cover back somewhat frequently for loading taller items. I also like that I can roll it completely back and the rearview is not obstructed in comparison to some trifold tops.
Another option I have been looking hard at is the Roll-N-Lock MXT with the option to add some Billie Bars (or other brand) on top with, rails, a platform, or basket. Seems to be a pretty versatile option and seems that cover has some good reviews.