We used the Eibachs for a 2.5TDi Quattro Avant on Craigs S4, as the axle weights most closely matched those of the original S4 Saloon springs.
I figured that the weight of the 2.5TDI motor would roughly equal that of the S4 lump (two small turbos and 30v heads against a big turbo and a rotary derv pump...)
They seem to work just fine, if anything the rear is a tiny bit high when sitting empty, but i'm sure that when its on the road with people in it it'll sit just right.