Just before you invest in the new fan ("extractor") I'd tell you a recent experience. We too, remodeled the master bath and replaced the older, inefficient vent fan. The builder used an electrician to do the install, although it was fairly simple. The same duct work was used to vent the moist air to the ourside. This happened to be through the roof. It was very noisy... rumbling, almost. What was found, after replacing the fan with a new one (thought there was a problem with the first one) and still having noise, is that the little "flapper" door that opens and closes (closes when the fan is shut off to keep outside air from filtering back into the bath) was stuck in the closed position. It had, over the years, built up "gunk" which inhibited it's movement. Once that was replaced, the fan worked very well and quietly, as advertised.
You may want to check that out...