I got an Achilles tendonitis/tear from Kona-Xterra double and saw my ART PT today. He always ultrasounds me for just about every issue other than the standard ART stuff. Can’t really tell how well it works (since I haven’t done a controled experiment 
but I trust the guy who does it…he believes that cold gets 1/4" below the skin, laser therapy can penetrate 1/2’ and ultrasound up to 3/4" into the body…he mentioned the home device today and said he thought it should be useful, just not as powerful as the one he uses and would require more application time, which the charts on that web site bear out. I might be a buyer…will be back to him tomorrow and see what he says when I ask him a pointed question on me buying one.
I also have tried the battery-operated home electro stim for other things. My PT lent me one, but he has never used one on me. I don’t think they do much, and in fact the unit’s instructions says they are only for “alleviating pain”, but I am sure they are a great revenue enhancer for a chiro…