Congrats on the SHO! They are amazing machines. I just went through this process, and both LMS and Unleashed are amazing tuners. I went with Unleashed because I liked the idea of the tune being customized for my engine vs a one size fits all method. I have read many, many reports on both tuners being absolutely amazing, and you will not be disappointed with whom ever you choose. That said, my Unleashed 3 bar tune has my SHO in the 12's on the first revision, and she has a little more in her. Just read, read, read, and then decide for yourself. Either tuner will take great care of your car. As far as warranty, tune could potentially void your warranty, assuming they can prove the tune was the cause of the part failure. Most just return to stock for warranty work, while taking note of the strategy code, and then just retune once they get home. Enjoy that beast of a machine! Nothing greater than watching a Vette, 5.0 Mustang, etc., in your rear view mirror!
Last thing, WELCOME TO THE FORUM!