Hi guys,
I can tell you that the Bilstiens failed miserably, And the dimensions of travel are the same as the Pedder, or Gabriel shock (maybe there was 2-3mm more on the bilstien)
What I can tell you is that 1 Shock per corner is enough, The spring does most of the work. In the case of a Coil, or worst still, piston or bellows airbag is that the lack of friction to reduce the rebound rate, makes them somewhat more difficult to dampen.
In my experience, Leaf springs seem to handle the loads better on corrugated roads, giving better feedback to the monkey trying to keep to Itinerary. We tried this , that everything, but you need to look at the whole package, Set up for what your doing, and In most of our cases we can because our (FG's), meaning your and my FG's are not used to go to the supermarket, or drop the kids off at school, even though we may do it for fun from time to time.
BTW, Tried the Powerdowns, as they were the only shock that lasted on the 0303 rear engined mercedes buses that we converted to 4X4 for fraser island, and they were 4 bag rears and 2 bag steers.....But no good on Cape York, overheated and dumped the gas, just like the Bilstiens.