I don't use Vuescan regularly enough to give you an authoritative comparison between the two applications in respect of resolution settings. As for SilverFast, the Scan Dimensions Panel, especially with the Expert Options open (Ai 8 Studio version), gives you complete control over the relationship between input resolution, output resolution and image size, including the ability to adjust all three coherently. There may be free resources on how to use this fully populated set of features from one of the videos accompanying the application or downloadable from the SilverFast Website or the compact application guide, also available there. For more comprehensive and detailed instruction on using these features, if you subscribe to Lynda.com you can find a video tutorial on SilverFast 8 authored by Taz Tally, or you may obtain my book on SilverFast 8 from the SilverFast website, where Chapter 5 explains all this in considerable detail.