I inherited a stove when I bought this house last year. After scraping out 20 years of hardened clinker I worked out it was a Jotul No 6 which seems to be well regarded but is perhaps 30y old or thereabouts (maybe dating back to the original house conversion).

It seems to work pretty well but at 14kW max (8kW on a 4h refuelling cycle) is a bit bigger than I’d choose – we don’t have unlimited wood and even if we did I don’t want to spend my life chopping it. As it is I run it quite gently which I hear is usually less efficient than a hotter burn. Previous owner had half filled it with fire bricks perhaps for the same reason. Probably 5-8kW would be about right. I’d also like a glass door if it didn’t always need cleaning – opinions seem to differ as to how clean they keep, probably depends on the design.

Am I likely to see any real benefits from a new stove? Or is it just a waste of money to get rid of something that works as it is?

What is its main purpose? As a main source of heating or just to supplement the living room when its chilly?

14kW is massive! Our 8kW i find almost too big, its a bit fuel hungry. Also got a little 4.6 kW which is good. can burn it a bit hotter without it munching through all the wood.

Id go steel. Heats up faster. Most stoves these days seem to have airwash systems to keep the glass clean. But burning hot will keep it clean anyway.

Id go multifuel as coal is nice for the weekends and just keep it going all night too, but this depends if you mainly use central heating?

As Chris said, unless the stove is the sole heat source in a very large room, 14Kw is pretty big. Chances are it once was the major heat source for the house.
You certainly can change to a smaller stove and this will use less fuel (which is good) and allow you to run the stove hotter – which is much better.
If you’ve got some spare cash then go for it but be ready for the installer to say your flue needs relining!
Don’t forget the old stove will sell on eBay to help offset the cost – Jotul are good though.