Hi ! I met Francois yesterday (yes, the dude who is so helpful with strings, he's a nice guy in person too ! ) and we did a few tests with both the Workingman 10 and 12, with my AUB and his EUB.
-The WM10 is not as loud, yet not as heavy as the WM12, well, you must have all guessed that.
-Both amps are VERY alike in terms of sound, same family !
-The WM10 is more tight, focused, and fast to respond, but that is very subtle. The sound is a little bit more natural. Alas, it lacks some bass, but you can boost it with the EQ. I also had to cut some treble to get a good sound.
-The WM12 has better natural bass, more balls. While it is a little (very subtle) less natural, I could leave the EQ flat... what helps keeping the sound more natural. Boosting the bass can be funky, but less natural. I had to cut less (or no)treble with it, than with its little brother. So the sound ended up being a little better.
I beleive the EUB sounded better with the WM10 while the AUB was better with the WM12. Maybe because we expect a very focused but less natural sound from an EUB.
Francois hits the strings with the side of his fingers, while I rather hit them with the tips of my fingers (electric bass antecedents, I guess). In the same setup, he could keep the treble at 0 or even boost it while I had to always cut some treble.
So, both amps are great and very alike. The choice can be more a matter of weight and volume, because the sound is very alike. If you prefer the natural quality of a flat eq, the WM12 is better, as you might have to boost the bass on the WM10. But again, the WM10 responds better, and an extension cab can sound just as good but louder.
I hope this will help someone and/or raise a debate !