I'll log my experiences here if that is ok.
Got my device. Just learning to use it but seems fairly simple.
I did 5 minutes on low around my knee and bit on stomach 36 point.
Zero heating of tissue, no noticeable negative effects.
Will take a walk in a few hours and see how the hills feel.
I wasn't having any specific knee issues but sometimes that one can complain,
so seems a reasonable test spot.
Will try on the left ribs / splenic flexure area in a bit.
Nice that the device has a warmup feature.
Nearly silent when on low but I could hear the buzz.