I was working w/ an Epson multi-function a few months ago. I got the scanner working over usb just fine, but didn't have success w/ using it over ethernet. I got the Avasys runaround too, but it looks like they are doing things differently now, so I might try again.
For your stylus SX420W, it shows the full printer driver and a generic driver, but you said the printing works fine, right? It also shows their iscan program
and also a network plugin package
. They have both as .deb packages (32 or 64 bit), but I'm not sure if they're compatible with LMDE - you can try if you haven't already. The iscan also has source, but the network plugin doesn't.