Should I replace all switches when renovating?

No, that is not necessary. Any 230 V switch or push button may be used.
You can choose the design that best suits your home.
By using push buttons in the system you have more options, as you are able to press one, two or three times to call up the different scenarios. For example, in the living room you could programme your push button as follows : Press 1x to watch TV, press 2x to read, press 3x for all lights to come on at full intensity.