I have been playing with IDT since its release. I used to play 1:8 gas and 1:10 touring many years ago and then changed to race Mini-Z some years ago. My last Mini-Z was MRX (Mini-Z modified with X-power parts) and I found the Mini-Z has pretty much reached its limit and there is not much breakthrough over the years. Ever since X-power IDT came out, I have been racing it and really enjoying these days. It's basically a scaled-down version of the 1:10 touring class. It's settings and characteristics are just like the 1:10 touring cars. But because of its smaller scale, the actual speed ratio is a lot higher than the 1:10 touring class. It's a very good "practice" car for me to get back to 1:10 touring.
When I have time, I'll try to write up a more detailed sharing experience report.
PS: I totally agree that you cannot really compare IDT with the Mini-Z class cars. They are just different.