Potenza RFTs do have their advantages. They NEVER wear out and give very good grip. Also because of the nature of the hard sidewalls, they give very little flex when cornering so feel really stable IME.
OK, they give a terrible ride (on a Z4) and potentially are responsible for more cracking and buckling wheels than is acceptable.
RFTs on any BMW with decent suspension are absolutely fine and I doubt you would notice the difference.