The castable resin from formlabs has been available for some time now. (December2014)
The resin burnouts perfectly with no residue. The only problem is that the quality of the prints is not as good as with the other Form1 resins. Another issue is: What type of metal would you like to cast?
I’ve had great results casting white and also black resin that aren’t supposed to cast well.
But the reason is that I was using a Crome-Cobalt alloy combined with a high temperature oven and high temperature investment usually used for dental plates.
So it really depends on many different aspects.
Ill attach a photo of a dental plate casted with formlabs white resin.
Excuse my poor English