I just picked up an IDX Pro with Mr. Bills mods. I lucked out and found one in excellent condition. I've been using the Whites 5900/6000 series for over 20 years as my main detectors and tried an IDX (unmodified) a few years back. It was a good detector but I wasn't impressed as far as depth enough to keep it long. I spent some time bench testing the new Modified IDX Pro today and then hit my 20 year old test garden. I don't rely on air tests when it comes to depth in real world hunting conditions but damn Mr. Bill, I don't know what you tweaked but this detector will air test a silver dime quite a bit further than any detector I've ever owned and I've owned quite a few different makes thru the years. Ground balancing was easy and it picked up everything in my test garden with ease also. Now I need to take it to one of my ghost towns or lumber camps to see how it performs at these Iron infested sites. I'm impressed with the detector and especially Mr. Bills mods. so far.