Gian Robert derailleur's as far as I know came out in 1963. We stocked them at the shop I worked as a schoolboy. The shops owner got a couple from Ron Kitching and he always put the stuff on trial before selling it. I was lucky enough to be given one to test for him. What I can remember was it was ultra-light and shifted well but no match to the Campag Gran Sport. These were in the same price range as the Simplex Prestige 532 and had to compete with this mech. This make of gear were still available in 1981 from Kitching's. There was the Gian Robert "System" and the "Campione" still available then. I never saw many of these gears used and always regarded them as a rarity. My old mate Tony Oliver use to get a lot of discounted stuff from Ron Kitching and he had some of these. Could not shift them for love or money. If you want to be the odd one out in the bunch this is the rarity to have. Finally the shop I worked in was Playland of Stevenage the owner was Mr. Vic Butcher and he had three shops in the town. A diamond to work for and did much to help promote cycling in this part of England.
Best wishes and be lucky. Michael Butler Huntingdon UK.