Con: If you don't know someone with one already in stock with all the parts (checked and re-checked). You'll be waiting a long time to get your hands on one, if at all...
Con: If you think your truck leans now in corners and doesn't handle like a race car. It's only going to get worse... The body roll will definitely increase. Even with HD springs all around.
The cons don't outweigh the pros in my opinion though.