I think it is worth it. 105 is a good length especially if you like to mess around during your free time to photographing insects. If you just want to use it for rings, you dont really need 1:1 macro and you dont need that long of a glass. It is probably best to shoot detail shots with flash when there is not a lot of light. But sometimes you dont want to shoot it with flash. That is when it is kinda nice not to have that long of a lens to minimize motion blur. If I had to redo my purchase, I probably would have bought 50mm macro lens. 1:2 magnification is plenty and you dont need AF for macro.
