Yeah I know what you mean I don't know how rare they are I've never seen one for sale on here before. It does shoot better than an 11 in my opinion. But like you said its not an up to date performance marker.IMHO people in the market for something like that are not looking for performance as the top priority.
I think it's more of a curio/collectible that also happens to usable. As such the pricing is much more a matter of finding the right buyer.
If you just want to unload it, price it like a regular 11 and it'll probably go like snap. I just missed a Pink Lady Ego 11 because the seller literally had people in line waiting to buy it for a "typical Ego 11" price. She probably could have asked 100 more and maybe one or two buyers would still have been interested.
It's whether you want the best possible price or the deal done fast...