I can't comment on the Quadzilla's performance, but I do have both the Quadzilla Commander and Edge Hot Juice w/Attitude mounted in my truck.
If I had to pick one, I would go with the Edge in the A-pillar position all the way. The *only* thing the Commander has that the Edge doesn't is the fuel pressure and rail pressure. What the Edge has that the Commander doesn't is:
1) Engine trouble codes retrieval and reset
2) Turbo cool down timer
3) Performance measurement (0-60mph and 1/4mile times)
4) Intake Air Temperature
5) Transmission Gear & Slip
6) RPM's (Quadzilla says they have it on their web page, and they have a wire for it, but the feature is "not yet implemented)"
7) Speed (the steering wheel blocks my view of the factory speedometer, so I actually use this feature a great deal)
8) I think a few more things that I can't remember just now.
The Commander will do backdown on trans temp, but the Edge does it on trans slip which makes more sense to me. They both do backdown on EGT & Boost. The Commander will do it on other things, but you would never use the other things in practice. At least when controlling the van Aaken box that I bought the thing for, the Commander does backdown in 0, 50% & 100% increments. The Edge has much smaller steps. They both have cold engine protection.
The Commander's LCD display is bigger, but much poorer quality. The dots are way bigger, the resolution is poorer, and the display is laggier, so you see a lot of ghosting as the numbers change.
Unless you have a totally built truck (and see my profile for the complete list of mods on my truck), the Edge Hot Juice has more power than you have mods to support. With my basic Flux 1 injectors I cannot currently drive on level 6 until I upgrade my CP3 past the Relentless DIY mods. There was a while before I did the injector mods where I had enough air to make level 6 a daily driver in cold weather (i. e. dense air) conditions.
Currently I have the Commander on the A-pillar (because they only make an A-pillar mount for it) and the Edge on the overhead mount. I'd rather have it the other way around because I use the Edge more, and the visibility in the overhead position is not nearly as good as the A-pillar. Nevertheless I really enjoy having simultaneous display of 8 parameters.