I think the beauty in the Suntour design was how the angle of the parallelogram allowed the wheels to stay close to the cog instead of just in and out. It was a simple and elegant design. They won. They build the better mousetrap.

The compromise in the Rally first gen design is in the rotation or the pivot point at the frame attachment. I don't know what they were smoking when they made gen 2 unless Shimano got onto them.

As the chain is slackened the jockey wheel goes forward which takes it in closer to the smaller cog. As it tigtens it goes back but the problem is that the front chainrings influence the tightness of the chain and the relative position of the jockey wheel whereas in the Suntour design that position is based on the derailleur itself.

Perhaps I never had a problem shifting with the Rally because I never used it with a triple but only with a standard 42/52 chainring combo and I only crosschained once through the entire gear sequence on the middle cog. Of course I also never shifted it under pressure. I know when we built our tandem we used a Suntour