While I like SunTour as much as the next guy - and the V-GT really is an excellent piece of kit - I also like the earlier Shimano derailleurs. I'm not familiar with the Lark, but have experience with quite a few that were introduced in the seventies: Crane, Titlist, Altus, and 600. They all work well to very well. Especially the Altus, with its Centeron mechanism, impressed me.