WEI is a very imprecise, general way to benchmark your system. You're probably going to want to run a benchmark specific to photoshop with either card, such as hardware haven's tests of you want an objective result. Look around for other options, of it dosen't work for you. PS does do some offloading to the GPU, but this is heavily dependant on what version it is, and well the size of the image and other factors.
Practically speaking though, I suspect thats a great price for a card of those specifications, and since you already have it, you might as well make use of it.