I’ve recently got to try one of these, and already noticed a few interesting effects. Used together with meditation it can keep me grounded to my body (it’s kinda hard to ignore a few thousand little spikes poking your back! ). Together with mindful breathing and doing a body scan it can create a very intense physical focus.
The spikes have also helped me with mental blocks and restlessness, and given a temporary relief to muscle and joint pains. I haven’t tried acupuncture or acupressure (yet) but I’d imagine this would be a kind of “brute force” approach to that - just poke every single point there is, you’ll hit the right one inevitably! There is also a strong endorphin “high” after getting up from the mat that feels pleasurable. I’ve heard of people falling asleep on these but I don’t think I could do that, even though it’s lovely to use just before sleep.
Have you tried this curious little device that looks like it belongs in a torture chamber?