I have both.
Topping off tanks with the Yong Heng is an adrenaline-fueled babysitting assignment that feels like it's going to blow off an arm or half your face at any moment. I'm not suggesting that's truly the case or that they're dangerous, but between the 140dBs auditory rape, the thing walking away as it operates, the manual air bleeds every 3-5 minutes.... it's just high stress. I don ppe in the form of ear protection and safety glasses when the Yonger is rocking and rolling. But it does top off a 45 or 60 min SCBA surprisingly fast.
The Altaros is exactly the opposite. Turning it on is a quiet and leisurely stroll in the park. I can sit in the gunroom while it operates ten feet away, while working on a gun or some other airgun tinkering. Or more frequently, I turn it on and walk away. I tend to run the Altaros on my days off. While I'm mowing the lawn, or spraying weeds or any number of other honey-dos, the Altaros is quietly and safely filling my tanks. Occasionally it'll be movie night with the family and the Altaros is out in the gun room topping off the tanks. Many talk about the speed of filling with the Altaros as a negative, but I view it as a positive. Less heat means longevity. And it's not doing it all at once so I don't have to stand there and babysit.