Hi Blair,
I have used Hagon rear shocks on two Airheads and they have been OK. I haven't used either of the others so can't compare. I still have the BMW standard shocks on the 1150GSA.
I did split a Hagon top mount but that was probably my fault by loading it when removing the rear swivel bearing on the 100GS.
Dealings with Hagon have always been fine, plus you see them at the big shows if you want to natter and look at alternative shocks.
See you at the 'pre '65' at Kinlochleven ?
Bob.