I have the 791xv. Its awsome!
Range is excellent. Features are easy to use and there is lots of room for expansion/add ons.
Make sure you get it installed by an experienced authorized shop. I cannot stress the value of a good install on an alarm this complicated.
The DEI product line is better than the Compustar crap and other look-alike 2 ways. Installed properly it will cost around $600-700.