On MK4 printers and later, the only thing the stealth mode seems to be doing is slowing down the bigger linear moves. I don't notice any difference in sound otherwise. The fan is what you mostly hear.
It works with real-debrid, there's just fear that real-debrid's content will be reduced by the outcome of the latest lawsuit. I've switched to TorBox because of that (and the lower price), but I honestly haven't noticed any degradation of the real-debrid service yet.
On MK4 printers and later, the only thing the stealth mode seems to be doing is slowing down the bigger linear moves. I don't notice any difference in sound otherwise. The fan is what you mostly hear.