With a little research, it appears that Red Line 10W-60 more closely matches TWS Motorsport oil than Edge. It has a Viscosity index of 182 and slightly higher viscosities at 40C and 100C.
http://www.redlineoil.com/product.aspx?product=11704
Too bad they fail to mention that it is recommended for Z3M/Z4M's (however they get every other S54 application).
Maybe Redline is worth trying out.