How good are these EMS/ Ultrasound devices for recovery/ rehab?
Well that page seems to be mostly TENS units. So those are the EMS type of thing and use small doses of electricity though electrodes place directly to the pain area on the skin. They do have and ultrasound link on the side bar but I'm just pointing out that these are very different things.
Ultrasound is a way of taking images using ultrasonic waves (very high frequency sound waves). These reflect off the tissues and these reflected waves are used to make a picture. The advantage of ultrasound is it's very good for a quick diagnostic view of soft tissue structures. Different tissues have different desnities so reflect the waves differently making it possible to visualize them. When you use ultrasound it does produce a small amount of heat. It is this heat which is postulated to speed up healing of injured tissues. Evidence of effectiveness of ultrasound? Hardly any good evidence at all and I'd say it's right up there with acupuncture.
The evidence concerning TENS is all over the place. There is better evidence for pain relief than for ultrasound but even so pain relief in itself does not mean healing. It could be a antinociceptive response similar to opioids. TENS is also combined with acupuncture (when they deliver current to the needles). Long term effects or effectiveness is not established. I don't think there is enough for it to be recommended.
Well there might have been a big placebo effect. But I just destroyed that I'm afraid. Even so, placebo is mostly active in pain relief not in physiological healing of tissues (although "active" might not be a good word with which to describe a placebo effect).