i've had my diablo for a while now and fully enjoy using it. there's a wide range of adjustments that can be made with it (go to features page on their site, no need to list we all know the deal on these things by now), uploading new tunes does not take a long time at all, and the data acquisition tool is pretty good.
It is not really live data like they make it sound. It is live recording of data, played back at a later date. So if you think you're popping open your laptop and going 'bleep bleep bloop im 2f2f' then you'll need the SCT or one of the other more expensive ones
I honestly don't think any of the 300-400$ tuners are going to be arms and legs better than the next one. So look at the feature lists from each site and make an excel sheet and see which one has the most your looking for. Just because I really like my Predator, and someone else loves their Hypertech, etc. really doesn't mean squat since you'll be the one pressing the buttons and watching it tick 1% 2% 3% 4% etc.. when you put that first tune in..