ZZR 1100 outta rear brakes

I've run outta brakes on the back of the big girl. I've not had the disc looked at (to see if it can be machined), but I looks pretty worn.
So, I'm looking at replacing the whole rear. Local bike shop can get an OEM disc for a touch over $500 (
) a Goodridge disc for around $250 (better, but still...) or a Metal Gear disc AND pads for under $220.
Has anyone got any experience with Metal Gear or rear discs on big bikes at all? Should I go the cheaper route, or head for the Goodridge? She's got braided GR lines and GR discs on the front already.
Thoughts? Suggestions???
So, I'm looking at replacing the whole rear. Local bike shop can get an OEM disc for a touch over $500 (

Has anyone got any experience with Metal Gear or rear discs on big bikes at all? Should I go the cheaper route, or head for the Goodridge? She's got braided GR lines and GR discs on the front already.
Thoughts? Suggestions???