I believe quiet mode should limit the maximum output of the compressor.
I’ve only experimented with quiet mode briefly for central heating, and observed quite confusing results. At least on my heat pump (5kW Gen6) enabling quiet mode resulted in rapid cycling and higher current draw, lower COP and more noise! Based upon this observation, I would not recommend using quiet mode for central heating.
Interested to hear your observations.
Quiet mode seems to work as expected for DHW, it limited maximum compressor output, the DHW cycle took longer, COP was slightly improved and noise was reduced, although my Gen6 unit is quiet anyway.
