I have DEI products in both my vehicles...and I recommend them to anyone.
I have had the Viper 791vx 2-way remote start/alarm in my Expedition since 2003 with no problems. I have only had to replace the Key Fob once due to diving in the pool with the keys in my pocket.
I also have the Clifford 3.5rs Matrix 2-way remote start/alarm im my Escape. It was originally installed in my F250 back in 2004 and was transplanted into the Escape in 2005. I had to replace the Key Fob twice, once under warranty and once because my child dropped my keys on the driveway.
FYI...I have the older styles of key fobs on my systems which cost around $40 and are hard to find (they were discontinued a couple of years ago). I have heard that the new styles are even more, around $129. You need to ensure you take care of the key fobs because they are expensive.
AK4wheeler