Upgrade Or Replace?

I've been swithering for many months about the best way of getting a 45XX Small Prairie tank for the Minffordd fleet.First World problems, and all that, I know...Although outshone in the popular imagination by the Manors, Duekdogs and Collett Goods, they saw a lot of use at the northern end of the Coast line, working from Pwllheli and Portmadoc sheds, and often entrusted with the Cambrian Coast Express.Right now pre-orders are being taken for a brand new version of these go-anywhere ex-GWR branch line engines from Rapido.If it's anything like the Highland Railway 'Jones Goods' I already have it will be a superb runner, and you can buy it pre-fitted with DCC sound.However, I already have a 45XX.It's one the Bachmann ones which probably date back the best part of 20 years.It's so ancient - I use the word advisedly - that it doesn't have a DCC socket, but it's a relatively simple project to hard wire a chip and fit a speaker and stay alive.This was bought second hand a couple of years…