Yep, loving my gesetzliche Krankenkasse (public health insurance, which is more like "highly regulated insurance"), even more than I liked the Privatkrankenversicherung (less highly regulated, but still with better guardrails than a lot of things I've seen in the States) I was on my first decade in the system here. Sure, there are some specialists who won't accept it, or who will give you a sooner appointment if you're private pay, but in that situation, you have the option of declaring that you're a self-payer that quarter, and your public insurance will reimburse in the amount they normally would have for that procedure or exam. For things like an MRI, the full retail cost in Germany is still much lower than in the US (it was about 600 EUR for my back a few years ago, while I was still privately insured, and I still had to wait for reimbursment).

Even once I do hit the income threshold to switch back to private (switching back to fulltime work), I'm pretty sure I won't.

As far as doctor choice goes, I feel like I have more on the public insurance here (like 90% of the population) than I did with UHC in the early 2000's back in the US. I certainly have fewer financial surprises.