Ok, I do this all the time, no warping and it will make the soap harder quicker. However I have a professional dehydrator so that may make a big difference. The one I use is large, bigger than a microwave oven, has very specific controls and a lot of space. I think it was just over $500 new.
So if you have one like this then definitely go for it, you won't be disappointed. You will notice a HUGE difference with castille soaps. However as others have noted the longer you leave it in, the less of a difference it makes. (I dehydrate at between 95-105 degrees)
Edited to add: It really helps when you make a rebatch, you can add more water to get a smoother appearance and then dehydrate the water out.