I've been using the red Gooey pads for a while now, having switched from Koolstop salmons. I originally only got the Gooeys as I needed pads in a hurry from the LBS.
Not quite as good as the salmons in the wet... maybe 90-95% as effective, but still miles better than the shimano offerings. In the dry - can't tell they're not Koolstops.
Wear is comparable - I'd guess on 2 - 2.5K before replacement. The compound is soft so rim wear doesnt appear to have been an issue, and I've not had to dig any flakes of alloy from the pads as per Shimano. Oh, and no sticky brake residue needing to be cleaned either.
I've just bought another set for the commuter bike..... TBH I see no reason to pay double for the Koolstops anymore.