I was a Crimestopper dealer for about 20 years. Last year I switched to DEI (Python/Avital) because I kept having complaints about poor rannge with the newest remotes and Crimestopper wouldn't do anything about it. I really didn't want to switch, but Crimestopper decided to kinda screw all of their dealers by now selling directly on ebay and other sites for almost the same price that a dealer would pay. Pissed alot of people off, and my distributor was one of them. They simply stopped carrying their product.
Python/Avital/Clifford/Viper are basically the same product with a different remote. Clifford and Viper are a Direct line (requires substantial quarterly commitment to buy X amount of product), while Avital and Python are available from distributors (can buy in much smaller quantities).
I was apprehensive about switching to DEI, because I had installed some of the older systems (with outboard relay packs), and wasn't impressed. Also the fact that I had done the Crimestopper usits for soo many years and knew them quite well. The new Python 413/411 & Avital 4103/4101 systems are great units and reliable as can be. They are reasonably priced and offer many features. They have excellent range and do what is expected of them. I personally like the Avital remote more than the Python, but otherwise these systems are exactly the same.
I have a Crimestopper RS4-G3 in my '96, but sometime soon plan to swap it out for an Avital 4103. The RS4-G3 remote was the worst Crimestopper ever made.
One thing to add - Remote Start installation is sometimes more important then the actual product. If it is hacked in, then sometime, somewhere it will fail.