Most troops will never use a sidearm like this, myself included. Everyones personal weapons are still the SA80.
It's mostly aircrew and some officers that I have seen with sidearms plus sone specialists like snipers. Hopefully a few infantry can clarify who among them is issued one.
Why did it change? Serviceability and cost. It's always down to cost. Yes they tested three weapons at least but somewhere the cost figures are better for this over x life span than the browning. Have I seen German police with the Glock?
The SA80 is praised and slated in the services so I would be interested if that's looked at in the next 10 years. Does anyone here know? You guys seem to know your firearms !