When I first switched to Macs several years ago, I decided to buy VueScan from Hamrick Software. This turned out to be a great decision. VueScan works as promised. It is a rock-solid scanning package with a lot of options. It does not take the middle road and simply provide a base set of features for all supported scanners (of which there are many). My scanner has a transparency option and it supported that automatically.
Migration Score
GREAT
Migration Options
Native Version Available
The "serial number works with all operating systems", so you don't need to worry about a thing.
How Good is the Linux App?
App name should be marketable
Has a nice app icon
Uses Tango icon guidelines
Slick UI that's fun to use
Killer feature people talk about
Good-looking website
Top-level domain name
Site has FAQs for users
Site has a User forum
Site has a way to contact the developers
Packages for Ubuntu, Fedora, and openSUSE