Like Rob said, it's the weight of the reel that high up on the bow that's the only 'draw-back' to them. I used one for about a year, till I found the reel-mounts that go in the stabilizer-holes. When you're at full-draw, you don't really notice the weight up there at all, but just holding the bow or when you're carrying it around, you'll notice it.

Personally, for the money, I think you're better off with the stabilizer-mounted ones.

Just my humble opinion.