I wasn't really happy with any of the existing F1s, so decided to build my own.
Carbon bits are all home-made (using a CAD package, pillar drill and dremel).
Tri-shock rear-end is something I always liked on the later RC10L type cars and works really well. Mega traction out of the corners and very tunable (even a 2lb change in springs makes a big difference to the cornering).
Weight distribution is optimised for outdoor circuits, and is perfect left-to-right at both ends, without any lead needed. Generally I run 4-cell in the rear slots, but can move the cells forwards if needed.