I went with Viper on my 2004 F350 and have had no problems with the system. The installer originally allowed for a 20 second (glow plugs) delay which was ridiculously long and I slimmed that down to 6 seconds which works fine for Arizona.
If you decide on using Viper, I suggest you don't go with the top-of-the-line remote (color display) because it's a bit clumsy to use. I have Viper with the standard LCD screen remote on my Raptor and it's much more user friendly. A color screen really doesn't have much to do with anything related to starting a truck...lol.