Reply to CDJ900/CDJ2000 Advanced HID Glitches/Questions

I have a few questions about the CDJ900/CDJ2000 and the Advanced HID function, for those who have regular access to this kind of gear.

I've played regularly on the S4 for the past two years now, and I love the workflow, but I'm beginning to have my doubts about keeping it as my main setup. The unit is good, but the build quality is atrocious. I've gone through two S4s so far, and my current unit was defective out of the box, but playable. I had it repaired a few months back, but now, it's giving trouble again. I'll talk more about that in another thread. I'm considering switching to a modular setup of a DJM900 + (3-4) MIDI Fighters or CDJ900/2000s when the club has them available.

The other evening I got a chance to play using a HID setup of two CDJ900s, and a DJM900. My computer only has 2 USB ports so I had to use a USB hub to connect everything. I figured the DJM900, as the soundcard, was the most important piece of the setup, so I gave it a dedicated USB port on my machine and it worked great. Then, I connected each of the CDJs to a hub connected to my other USB port. I followed the instructions, plugged the CDJs in and selected the decks, and all worked well initially, but then I noticed a few glitches.

First off, I moved the platter on the CDJ for deck A, and noticed a corresponding movement on the HI EQ knob for that deck on my screen. That didn't go away.

Second, when I pushed the load button on the CDJ for deck B, it stopped deck A, a potentially disastrous club situation. That didn't go away either, so I avoided that for the entirety of my set.

My question is, why did this happen? Was it because I plugged both CDJs into one USB port? Is it possible for the MIDI signals get mixed up somehow? I've also heard that the HID works better on the CDJ-2000s. Should I avoid using it on the 900?

Before I start playing out with this setup, I want to be sure that everything will work correctly. The problem is, I don't have enough hands-on time with this gear to be able to troubleshoot, so I'm hoping someone more experienced with this setup can help me here.