ISIS drivers are sable but so is good Twaindrivers also. Twaindrivers for “professional” scanners are stable and good. No limitations in Twain, just how much work the manufacturer puts into the driver. Usually there is no problem controlling all features by Twain, specific features are controlled by custom capabilities. Twain has often a bad reputation of beeing less stable than ISIS . but as far as i am concerned, the most prominent difference is that these two formats can not be scanned in one scanner, in other words, isis need a professional scanner while twian picture needs another.