I have an Epson 4800 dpi (optical resolution) flatbed with impressive D-Max specs of 4.2. It's even capable of scanning 8x10 film.
However, having compared the results with my Nikon 8000ED dedicated MF film scanner with optical resolution of 4000 dpi, I find the Epson flatbed produces blocked shadows, implying the D-Max spec is highly exaggerated, and lower resolution, implying the lens is inferior.
The resolution difference might be analagous to using an 8x10 LF lens on a 6x7 MF camera as opposed to using a dedicated (and sharper) MF lens on that MF camera.