Great point. On a 'street' engine that puts out enough power that you have to run forged pistons, making sure the engine gets to operating temp before it's driven is always a must. However, on a real street engine, cast pistons are the way to go. They aren't as flexible as forged (which is why forged pistons are used in race applications, they can handle adverse conditions [read detonation] better than cast can) but they do substantially better than forged units during cold start and winter driving.
... Could be why I don't ever understand people that think they need a 1000hp daily driven car.
Anyway, if you cant find ITM's, 1 fast z sells good cast pistons, and I think he may have the turbo CR as well. His company is B&M Machine, iirc.
Also, keep an eye here on the classifieds, a set came up about a month ago of NIB ITM L28ET pistons.