Independent BMW maintenance vs dealer, is it actually worth the switch?

I've been loyal to the main dealer for years mostly because I was scared of voiding anything or ending up with a garage that didn't know what they were doing. But the last few visits have left a bad taste, especially the way they pad the bill with things I never asked for. So now I'm actually considering an independent specialist for routine maintenance, and I'm trying to weigh up the pros and cons properly instead of just reacting to one annoying invoice. A friend sent me a page that breaks down what a proper maintenance schedule should include and I wanted to view details on whether they follow the official intervals or just do whatever's convenient. That part matters to me because my car is still under an extended warranty and I don't want any grey areas if something goes wrong later. For those who've made the switch from dealer to independent, did you notice any real difference in quality or did you just save money? And did anyone have issues with warranty claims afterward? I'm leaning toward trying it but I want to hear the bad experiences too, not just the success stories.