Have you been cleaning it regularly as they recommend? (Which with the old models is a pain) - it might need a little cleaning. My F280 was quiet and then got more noisy. So I replaced with the F350 - very impressed so far.
I have a single 280, and have just gotten used to hearing it at 60%+ (I have mine set to max out at 90%). It sounds like the 3rd generation is very quiet, haven’t seen one in person though. Do you miss the extra flow from the 280???