Love driving on twisty mountain roads! I really miss driving with a manual. I've had several sports cars in the last 50 years all of which had them, and I always enjoyed driving on curvy roads, especially in the mountains as you have. The BMW auto is probably the best out automatic transmission available, and I often use its paddle shifters, but Lord do I miss the clutch and gear shifter! Some days I'd rather drive my old/sold under powered 1972 Spitfire than my M40i!
I think I read somewhere the additional cost of a manual in the Z4 is very high. That's why I doubt BMW will sell very many. When I was looking for my Z4 back in 2020, I seriously considered the Boxster simply because of its transmission. But the thought of repair/service bills even higher than on a BMW kept me away! I also briefly considered the Toyota Supra, but crossed it off the list because no convertible was available.
Doug