There's a lot of good points in this thread, but what about saleability?
We all have to sell up one day, or our heirs/executors do, or worse the local authority of you are intestate and have care bills.
When you sell, it's reasonable to assume that the buyer, valuer and surveyor they engage won't have the nuanced understanding like the people commenting here, they will just tick a box that says "DG - no" and advise buyer to negotiate the price down or look elsewhere.
At almost 70 I am realistic : I will be selling up my slightly too large and awkward house in about 10 years time *. Any work I do now has that in mind, conventional, good quality, easy care and saleable. (I'm not cynical, I'm not saying do it cheap but make it last 12 years si it's someone else's problem). Were I 35 and content to live where I do for a long time I might take different decisions.
So the DG or not question has a non technical, aesthetic, human, dimension. Only you can answer that bit.
* keep an eye on market place for lathe, Bandsaw and pillar drill sometime around 2030.
Wise words thanks. I am 37 and we are looking at extending as we have four children in a 3 bed house. I dont particularly like the style of house but the location is spot on for how we live. The ideal would be to build a heavy timber framed autonomous house but my wife has zero interest or inclination so the only other reason to move would be a small holding or somewhere with outbuildings for a workshop but unfortunately they seem to have gone beyond our budget in the last five or so years. So based on this I want to do the best i can with what i have so as Jacob keeps saying the correct design and finish.
Thanks to you and all others this has given me a lot to think about.