It gets into this weird territory though, where it's really products to get around quirks of old tube amp designs, or to get around bad designs like poor volume control tapers.
I ended up selling my Fryette PS-2 because I felt it was unnecessary with the amps I had at that time - master volume, power scalable modern designs.
I don't even remember how I talked myself into buying a Fryette PS-100, but before it broke I was actually about to sell it too because I again found it unnecessary with the kinds of amps I had.
Like sure, my Mark V ch1/2 do sound a bit different if I crank them up to poweramp distortion, but they don't sound better that way. Just different.
Yet people keep buying 1950/1960s tube amp designs and then pairing them with attenuators gives them a different compromise from power scaling and master volumes.
The IR-Load will be no different in this regard. That reactive load won't be a perfect fit for every amp out there, and the biggest problem it solves is making the re-amping solid-state amp behave like a tube poweramp, which then allows for a poweramp at a smaller size, weight and cost than the Fryette PS-100. In stereo too.