Up grading Potterton Profile?

Currently we have a Potterton Profile 55e that works well and is very reliable.

Due to changes in the layout of our heating we tend to run it at a low return temperature, as hot water is done purely by solar.

Would like to change existing gas valve to a variable (modulating type) to reduce boiler cycling when coming up to house target temperature.

Does any one have experience of doing this.

Our plumber says he has heard of this being done before and if I can source the parts he is willing to fit and commission system.