I've owned BMWs since 1983 and I would not hesitate to buy a BMW manufactured at the Greer plant. The only reason I haven't bought a US built BMW is because I much prefer sedans and coupes to SUVs.
When the plant opened it initially only produced E36 3 Series sedans so that the build quality could be compared to that of 3ers manufactured in Germany. Only when Munich was convinced that the Greer plant was up to snuff did production of the Z3 sports car commence.
I remember having a few of those E36 sedans as loaner cars.
Yet the vehicles from that plant carried WBA VINs, until the guvmint told them to cut out that practice.