Yeah, Aquaforest does not recommend doing large water changes using the Probiotic salt. I've done 30% water changes with it, and I didn't get any bacteria bloom or anything. I'm not sure I wold try bigger than that.
The third component is chloride free mineral salt.
I've done a 50% water changes with the probiotic reef salt and no bacteria bloom. I think you have less chance of a bacteria bloom with a mature system.