My favorite rear changer was the Titanium Huret super sucess made in the late 70's and early 80's. It was quite light at 165 grams and used a deeply toothed upper jockey pulley which had adjustable ball bearings. The body had two holes to mount the deraileur cage, the upper for 24 t max, the lower for 28 t. The changer also had a "b" adjustment screw so you could optimize chain wrap for your cog set. I sent my Columbine to Bicycling magazine in Jan of 1982 for a road test with that changer on it. Doug Roosa liked the bike and shifting so much, it was 7 months before I got it back! The deeply toothed Huret upper jockey pulley would help NR and SR changers shift better also. It kept the chain from moving sideways shifting to a larger cog. Coupled with a judicious bent to the pusher plate part of the upper pulley inner plate, which decreased the distance between the chain and pusher plate, you could make a NR or SR shift considerably sooner. I have several new old stock Mavic changers, the adjustable cage was a good idea, but I think the Huret sucess series was more robust.
Paul Brown
Cycle Dynamics
Santa Rosa, CA