Based on my initial experience, wish I'd jumped right in. My first roll has been with Glow-In-The-Dark filament from ORD Solutions (what I assume is a cheap nonage company). Frankly, it's way easier to work with than the XYZ Filament - sticks better, corners and edges are cleaner, just simpler in every way. After days fighting with getting the XYZ filament to hold and not warp, this is a cakewalk.
The only problem I had was with the filament feed. I printed a spindle that hangs off the back of the Duo and promptly ruined a print when the external filament bound on the spool. After spending a couple hours and a trip to Home Depot trying to come up with a viable solution, I finally hit upon a really cheap, reusable and simple solution - I know it's only 2 days in but I don't think I'll top this hack in 2015:
