Made another bread with all ruchmehl - a Swiss "semi whole" wheat flour. Used some quite old unfed rye starter from the fridge (maybe around 25 g?), 450 g ruchmehl, 330 g warm water, 11 g salt. Mixed with a hand mixer and spiral attachments until moderate gluten development. Did three folds about 30 min apart, then left at around 28ºC for a few hours, until nicely grown and airy. Preshaped, and then shaped into a batard, left to final proof overnight on the balcony. Baked in the morning on steel 230ºC around 15 min with steam, then 210ºC without steam until good colour.
Again the ruchmehl gave a rather open crumb! It has 14% protein, higher than any flour easily available here. It makes a very nice strong dough. I can see why the Swiss bakers like baking with it.
This time the flavour is clearly a little more tangy (I guess due to low inoculation with unrefreshed starter and long bulk), but still delicious, and the texture is great. Very pleased with this bread, and I think I might just keep using this flour for everyday sourdough bread. Flavourful and so easy to use. I might compare to some German Type 1050 at some point, should be the most similar flour available afaik.