I tried the original 'battery' powered unit a few years ago, and was less than impressed.
I wanted it to increase the volume of my XM MyFi, so I could use the 'edset' speakers in my full face helmet, rather than earbud type head phones. While it did increase the volume some, it wasn't enough to be heard well over road noise and the wind noise in the helmet.
The one I tried said it would double the input volume, but I'd guess it really was more like 50 - 60 %. The one you linked to, says 4 X the volume, so it may work better.
Just my .02

Black Dog