Is the Shuguang 5AR4 any good?

I am probably getting carried away here, as I now have three 5AR4s on hand (which includes the one installed in my power supply) and one in the mail and bids in on 3 more (which I highly doubt that I will be successful on), but I just got an offer on a couple of Shuguang and I like having spares and I kind of have a hard time resisting a bargain.

So does anyone have any experience with this particular brand of 5AR4?