I have that Pace Edwards Full Metal Jackrabbit on my truck. It's a high quality piece and there are no leaks. I like the secuity it gives me over the vinyl covers but you do sacrifice some forward space in the bed. That isn't an issue for me. I think it's overpriced though. I think the Roll Baks cost about 35% less. You should look closely at both before you buy.

 

After some good rain in the area, I found that the canister leaked a bit around the seams. I placed some black duct tape over the seams, so it would blend with the black metal, and it stopped the leaking. I get 1, maybe 2 drops around the keyhole; but for the most part it stays dry in the bed.
I have the Pace Edwards Jackrabbit, with the vinyl over the metal. Racinbob’s right; it is a bit pricey, but mine came w/free installation, so that made it a little better for me.