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...I heard that Poppers can be used to manually control the qflash power like what the copilot does.
The JrX system, which you asked about, will remotely control the power level of Alien Bees, White Lightning, or Zeus strobes as is. If you add the RP Cube you can control Canon- or Nikon-compatible flash units. If you have a Q-flash Trio, it'll slide right onto the hot shoe of the RP Cube, and if you have a T5dR or similar you would use the appropriate QTTL module (the D22w-R in the case of your Nikon D800).
Don't confuse the RP JrX system and the original RP PX system; the former is pure radio, and the latter is an optical-to-radio and radio-to-optical translation system. There's also the new RP Nano system, but I have no experience with it; I do know that's it's a basic radio trigger, though, with no remote power-adjustment feature.