I do have one older PowMr 12v all in one with some real peculiarities that affect its function, and I've had some REALLY cheap PowMr mppts that didn't seem to work well. But i bought a newer version of the 12v aio and its been fine, and ive had some of the larger 40-60a standalone mppts that worked fine also.
Overall my opinion of PowMr stuff is that there's usually not a ton of options at the low low price point anyway so if the product 'mostly' works then its a win. My line of thinking is if something is 80% as good for 50% of the money it's a win. But i buy mostly stuff i dont need, so for people truly depending on the hardware, something with a more established track record might be worth the cost.