Trackday wets, 2nd hand?

As title really, is it wise to buy racing wets 2nd hand or will there usefulness have been and gone by then?

Once the edges have been worn slightly curved will they still give a greater difference in performance than a decent sports touring tyre?

(I'm looking at just trackday use at the moment) I have the 2nd set of wheels, just need to know what to put on them.

Exhibit A:
http://www.ebay.co.uk/itm/bridgeston...item19e00343a4

I'd go new with wets. They can loose efficiency rather quickly if run in the wrong conditions, it's not all about the depth of the tread.

Thought as much, just wondered if a worn race wet would perform better or worse than any other sports tourer?

In the wet, yes! Sports tours aren't great on track...trust me! Lol

[Red Herring]

If the tread blocks on the wets are still even (ie: they haven feathered) then they may still be worth having, especially if you only want them for track days. Check they aren't 20 years old (have a feel of the tread, it should still be soft enough for you to move about easily by hand). Even a worn race wet will be miles better that a road tyre in the rain, but if you use them on just a damp track you'll wreck them in just a few laps.