I have a Bambu P1S with an AMS after years of using a Ender 3 that was modified to high heavens both on hardware and on firmware level. It is a perfectly fine product and the AMS makes filament changes so much easier, it is a convenience that I personally love. My P1S is running in LAN mode and it works perfectly fine in combination with OrcaSlicer on my Linux machine. No data is send to the Bambu Cloud, everything is local.
Would I like the possibility to have a custom firmware on it? Sure, I always like options. But to be honest: My P1S runs better, smother, faster then my Ender 3 with his many mods and custom firmware ever did.
Is Bambu on my list of manufacturers for another printer purchase? Yes, but near the end after their anti consumer behavior lately.