Also note that the earth based systems are at the micro Tesla level. The high power ones are at higher levels - we are talking of milliT and below. So 1000 times stronger. More need not be more, but at the same time, some people respond to stronger levels, its all about your own body and tolerance.

IMO, one should generally manage with less, so why take a very high power system when you are going to use it less. Price matters. Bemer & iMRS are both MLM (multi level marketing) based products. That doesn't mean they don't work but they are expensive. QRS might be lesser priced and less fancy, but might work as well. I don't know how good Bemer and QRS are since I didn't have the opportunity to use them. Note I am product agnostic. I have used iMRS but that doesn't mean I'd whack the other products. Don't go purely by product supporting websites which push one above the other by saying zonks! i have this, that guy doesn't! At the end of the day, its your body and what works for you.
So if Bemer is what you can access and it works, go ahead!!

But generally, if you can, instead of purchasing, rent at least two types of machines for a month each and see if they actually work. The science behind these devices exists & they are not as contentious, as say, acupuncture.

The reason for trying out devices over the long term (at least a week or two) is that placebo effect is strong and long trials cut the fog away. Having said that, those of us in chronic pain are usually very attuned to our bodies and can quickly determine if something is working or not. So in short, be cautiously optimistic and trust your body.