I have used them at subsonic-- there is nothing to recommend them for that application really. They are not more accurate than SMK's, and of course at subsonic do not begin to expand..... and as I recall they ain't cheap.
I've used a couple boxes of 200-grain gas-checked cast bullets from Oregon Trail...... function, accuracy and economy were all good. It's been a couple years but I'm about to load some more. The only leading was a little bit on top of the bolt tail where the system spits gas on it..... easily scraped off.
http://www.laser-cast.com/trueshot.html