I don't doubt you in the least.
Furman even makes an AC power conditioning product rated at 20 amps, and they know the problem is so prevalent that they even state that they won't honor the warranty if there are "Field modifications" made. My attitude is that I'm protecting 15 amps worth of gear, so I want the unit rated at 15 amps, mainly so I can pop my breaker instead of the house breaker.
If anyone has seen a 20-amp Edison outlet, they'll note it's completely backwards compatble. So it's not like the outlet is gonna say "nope, wrong way, not working".
On a simlar note, my KV2 Audio EPack 2500 cables go from a 15-amp Edison(heavy duty) to a 20-amp Nema twistlock. The EPack WANTS 20 amps of current, but apparently they know something.... I've routinely run 2 of them, each powering a double 15-sub and a 3-way top(all being active driven) to PAINFUL levels for crowds of over 1000 people off a single 15-amp circuit and had headroom to spare, on the console, current and amp.
That reminds me, I need to buy some twistlock to edison pigtails for my KV2 Audio cables and a few others so I can work with a few more locations easier.(a few places I work have 20-amp 3-pole Nema twistlocks, just like on the KV2 Audio, except reversed gender since they are outlets!)
Oh, BTW, I have a 4-wire appliance cable I've modified for a 30-amp distro I have. That cable terminates into a 30-amp twistlock F, which mates with the M cable on the distro. I need to make a second one.(I have two distros). I can pull power from people's drier outlets, or this one venue that mounted one on the floor using my adaptor cable. For my Black & Decker generator, the twistlock goes right in.