I have the medium one for my four inch guy and it works really well. It worked for just over a year until the suction cups got messed up because he loves to pull all the suction cups off (And pretty much destroy things).

I added new suction cups and they don't fit as well and it sags a little bit but they do the job. He loves his ramp. I will probably glue them so they fit snugger. He's had himself and a few of his rocks up there (putting his rocks on his ramp and stacking them on the sand are another few of his activities

) before without a problem. And they are the really big ones, probably at least five inches in length and really thick. I'm pretty sure it will hold your guy. If he is destructive like my guy I would glue the cups on there.
I plan on buying the large one when we upgrade his tank and gluing it on there.
I love mine.