I worked with Giant bikes from 1992 to 2022 and never found them to be more susceptible to problems than the other brands we handled including Specialized and Trek, except for one specific model named Chinook, aka sh**hook. the brakes howled something fierce and we were able to quiet some of them, and not the others. As for proprietary parts, every brand has their collection of proprietary stuff (most of it unnecesary) and that is all I will say about that.