Does anyone here use "humidistat" extractor fans?

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I've had problems with damp in kitchens and bathrooms on a couple of properties, and was told by an electrician to install extractor fans in those rooms, with the fans controlled by "humidistat" sensors that detect humidity.

When the humidity in the room is above the set point (e.g. 80% RH = relative humidity), the fan comes on until the RH is pulled down to the lower set point (e.g. 60% RH). They should also come on e.g. with pull cords and the bathroom light switch, but instead of switching off when you turn the lights off, or even running on for a few minutes, these fans continue until they have reached that lower humidity set point - so they don't rely on tenants to activate them.

The problem with extractor fans is that tenants do like to turn them off at the isolator switch to same energy or stop noisy fans at night, so even the "foolproof" approach is easily bypassed!

I found some with Google "humidistat" e.g. at www.screwfix.com - the cheaper ones (£30) suffer from higher noise levels (so will be quickly turned off to prevent noise at midnight). The more expensive ones (£147) are quieter and should last longer (motors not straining as hard for the same extraction effort), but they might be more expensive to fit (larger diameter holes). At least they might be left alone by the tenants to do their job (because much quieter).

Can anyone share any experience with these? Thanks!