I have a Smarty and a Quadzilla Commander and I love them both, guess I'm biased but I don't have any complaints, maybe the Commander instructions are vague, but use your common sense and read it a couple of times.
The Smarty is something else! Lotta power-looking forward to 'turning it up' after my transmission upgrade. I don't mind the extra smoke, it only smokes when I'm stepping on it, I've heard of others who complained but it hasn't been bad for me. I haven't tried any other versions of the software. I have it on 90 HP with timing. I bought it because EVERYBODY spoke well of it, and now that I have it, I agree. What is cool is that it will 'follow' you when you upgrade your truck for more power. I'm not into bigger wheels so I haven't used the speedomnter adjustment, and I haven't set any codes so I don't need the code clearing, I just like the power. I noticed a small MPG improvement, probably would be more if I could avoid stepping on it.
The Commander is perfect for me-I want the multiple watching of different parameters but wasn't into all the gauges all over the place, with the A pillar mount, it's pretty subtle. I haven't used the data logging software yet (I just have the Smarty for mods so far) but I'll use it later after my trans upgrade and turbo upgrade after that. I have used the defuel thingy, it is convienient and helps keeping out of trouble. They are making boxes that work well with the Commander, like the Van Aakan C5 (in the mail from Imills Mid-Atlantic Diesel) and Quadzilla makes wiring harnesses to work with the other boxes like the TST and others.
What is good about both the Commander and the Smarty is that the customer service is just head and shoulders above a lot of other manufacturers and businesses. Other places kinda forget about you after the sale, but if you check out these boards, you will see a LOT of posts from both Bob Wagner and Quadzilla reacting to questions about their products.
Looking forward to the 'moderate' torque management of the Smarty (after transmission upgrade) and the 'wild' version too.