Haven't heard of anyone doing this, but....
if you're gonna tow, since you're considering the RAS I would think that's what you want to do, lowering really isn't a good idea. By lowering, you're going to reduce the load you are able to tow. By how much? I don't really know. If you plan to use the RAS for additional lean/sway control, the EE anti-sway bar that comes in the x-spec kit serves the same purpose and I don't think there would be much to be gained by doing both aside from the additional expense.