Ben are you talking about the liquid phosphate remover or the GFO based stuff?
Adam, I'am using the liquid phosphate remover from there but have only used it for less than a week so far then stopped as I have introduced new fish so can't say how well it works yet. I wouldn't recommend using it though unless you are skimming heavily and/or are using mechanical filtration as well. basically the liquid stuff binds to phosphates which then means it can be skimmers out or removed with filter wool. It can also effect your KH and PH as well as potentially damaging fish which is why I wouldn't recommend using it unless you have a sump and use mechanical filtration between your return pump and the display tank to keep it in your sump.
From the user accounts I have read and the people I have spoken to it is very effective stuff but it does have to be used with caution and IMO its not a permanent solution.
A HOB filter converted to a fuge can work very well. I'm actually considering building one to sit along the inside top edge of my tank as my sump is already crowded with stuff and is difficult to work in.