I use a Dual Scan IV on 10.5 with Vuescan Pro. Although it has some quirks, I find that Vuescan gives the best results. The Minolta software, which still works (!) under 10.5 gives much less refined results (crunches shadows, less output options, etc). Workflow-wise however, I would concede that the Minolta software is faster.
On the other hand, I found the support I got from Ed Hamrick (Vuescan author) to be excellent, and solved an issue I had with Vuescan within hours. Not bad considering we live on opposite sides of the globe.
Vuescan also has multipass scanning, and a reasonable number of sliders you can tweak to get the best out of your scan. It isn't the be-all of scanning, but adequate for an old 35mm scanner.
My film scanning software function wishlist is long, but it seems it isn't as big an industry as it used to be! I continue to assume that progress will be slow... (especially for discontinued hardware!)