I hope not to learn the hard way, but in 70,000 ish miles of BMW motorcycle owning, I’ve had two punctures, one drive bearing, one set of head race bearings, one switchgear. Only one breakdown when the K1300 had a flat battery due to the Garmin base drawing current, other issues picked up by the dealer, not bad.
I’ve three Ducati’s they never let me down at all, ST4, Multistrada and a Panigale.
Friends with other marques haven’t been as lucky.
So overall I’d say BMW were reliable and built well, certainly compared with Triumph and KTM, of course I may live to regret that.