Thermostatic mixing valve on an electric instantaneous water heater

[VWUK]

Any one have any experience on installing a thermostatic mixing valve on an electric instantaneous water heater for a basin ?

My concern is that electric instantaneous water heaters generally heat water above a comfortable temperature and then can not deal with the demand and go cold until you turn the flow down.

I'm wondering if a basin TMV will solve the problem or just create more ?

 

[Last Plumber]

Which heater is it, where is it installed, ( over/ or under sink) how many draw off points ?