I've had a couple of Leer caps both aluminum and fiberglass no problems with either. I just bought a used leer for my Isuzu Pick up. It is all fiberglass which brings up my next point.
Last new cap I bought was for my Nissan Titan. It was an ARE Impulse I had made to order. It had aluminum rails where it meets the bed. I like that. Glass rails can be crushed and deteriorate over time if you take the cap off and on a lot. That's why I bought the ARE. I was real impressed with that cap.
One other bit of food for thought on this cap. See how smooth it is? There is nothing on these sleek new caps to hold onto. I took a good fall off the back bumper of that Titan landing on my back. No harm done other than pride BUT OMG!. I was washing the truck and standing on the back bumper and my foot slipped from the soapy water. Nothing around that even offered any friction for my hands to grab just a smooth as a baby's butt, well waxed cap covered in soapy water. I got my racks installed on it right quick after that. Just something to think about.
I like that snugtop with the tool boxsides. I'd like to have those doors without the boxes inside just for cap access.
KISS Principle = Keep It Simple Stupid.
Your best defense against Murphy's law!