I haven't heard of the Pro Modeller wash before, thanks for the info!  I just picked up GW's Delvian Mud wash because I had heard great things, but I'm not impressed.  I'd like a high pigment content so I can dilute it as needed.  Any idea how the Pro Modeller wash compares to the GW washes, or if it's high pigment?  Thanks for your insight RobF!