I am not that familar with the compustar, but I do personally own an Avantguard 4. I am not sure the differences between that and the 5 but I can tell you I have had nothing but great experiences with it. I also added the Omni Sensor to my setup.
The features I had:
Keyless Entry
Trunk Release
Battery Backup Alarm
Chirp lock/unlock
Silent lock/unlock
Auto Start
Roll Windows up/down remotely
Turn Headlights on remotely
Auto Headlight on/off at dusk
BlackJax's anti theft keypad
Multi directional omni sensor (super smart impact sensor)
Tilt Sensor (any change in cars angle over a few degrees sets alarm off)
Proximity Alert
Grass Breaking Sensor
$3,000 anti theft guarantee
There are probably a couple more I can't
think of but that covers most of it. You also have 2 or 3 more programable functions, one of mine turned my neon on in the car.
The only problem I had at all was that proximity alert would trigger false alarms on my radar detector, so I just unplugged it from the alarm and didn't use it. But everything else was great.
I really loved the blackjax's system. It requires that everytime the dome light comes on (indicating the door has opened and shut) you are required to enter your 2 digit pin into the key pad. You have a star button and a blank. The star button you push for a number, and the blank for enter. So say your pin is 12, you would hit star, blank, star star, blank. The led light will then blink signaling it accepted the code. If you don't enter the code within 30 seconds the car will shut down (safely, won't shut down until you reach a low rpm) which allows you to call the police and retrieve your car. If you fail the enter the code the car reminds you with a chirp when you have 15 seconds left. Sounds like a pain but it begins to be second natrure. This alarm is currently in my mustang but I plan on removing it and putting it in my runner.