If you are drawing 8 l/min and then taps are turned on to ramp up to 14
l/min, then the pressure in the hot line will drop. The balancing valve
will
drop the cold inlet to the mixer to the same as the hot, preventing
excessive cold being drawn off through the mixer, keeping the temperature
stable.

You clearly live in a doll's house. When I turn on a tap, I get 30 l/min.
This would lead to a drop in temperature. Furthermore, the combi is likely
to be set to 60C output to allow dishwashing. Therefore, even on quite
moderate hot water flow rates, you'll be in the temperature unstable range.

Whilst the Mira is undoubtedly a high quality product, it suffers from a
vital flaw is that it doesn't have separate flow and temperature controls.
My mother uses the cheap thermostatic one downstairs as the Mira is too
difficult to set the temperature of and can't have the flow turned down.

I agree with the first part (but don't mind the high flow) and like to leave
the temperature setting alone and use the flow control as an on/off, not
experimenting to get the right temperature every time.

Christian.