Alarm for my 89 burb. Need input

I want to add an alarm to my 89 Suburban.  I am thinking of going with Commando 550 because they offer a 5th button on the remote.  I want to add another one to my wifes Xterra and that way we will need to only have one key fob.  Anyone have experiance with the Commando 550?  Issues or problems?

Also, I have a gate with a window in the back and want to controll the glass so that I can open the gate without using the key.  I want to use their 2 window module and controll one leg up and one down.  Or do I need the 4/2 window module. 

Looking for input and advice.

Thanks in advance.

Looks like a TRC alarm and for the most part installed correctly it can be decent. One problem is the Shock sensor, it is difficult to get set properly (causing false alarms. And yes the 2 window module should do up and down on the single back window.