Pressure Balance vs Thermostatic Valves

Am redoing the entire bathroom. Going from ancient three handle tub/shower set to either a modern Pressure Balance valve or a Thermostatic valve.
I am not clear on what each type of valve can/cannot do. Both are suppose to be anti-scalding.
Past problems have been, with an old fashioned design, that water temperature changes while under the shower head. Hot water source is a tankless embedded 5 gpm heat exchange coil.
Understand that Pressure Balance will compensate automatically for a change in water pressure, via hot or via cold ports, when dishwasher or toilet is put in use.
With regard to Thermostatic valve: How will the above problem be avoided? Does a Thermostatic valve adjust for a water temperature (within 3 degrees) change by opening/closing the water inlet ports? Given that the 5 gpm water heater might be overtaxed, will a Thermostatic valve be the better choice vs a Pressure Balance valve ?
I do not know which type of valve to select for the installation.
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