Olly, in my experience, 230F cooking temp is the main street for a never ending story.
You have to increase T to 275F and you will get:
1) better, much better bark
2) shorter, much shorter cooking time.
What happened to me was by chance.
I have thawed a marvelous piece of Prime 4 plate beef ribs by Creekstone Farm.
And I wanted to compare 3 meat rubs I recently received by US mail:
1) Black Gold by Texas Oil Dust
2) Ted & Barney's Meat Seasoning
3) Beef Rub by Moe Cason
So I did the...