Funnily enough, I experimented today with getting one of my models into SFM. Only managed to get the model itself in, though. No textures or armature (who knows what happened to them), unfortunately.
Blender serves all the purposes I need for my own work, whether it be animations, renders, or even pixel art, but if I could distribute my models on platforms like SFM, I imagine it would give me some publicity if nothing else, which is always a good thing when you're trying to make a living out of it. The model in particular I was trying to port got a lot of praise on my blog as well, so that kinda motivated me further.
Blender's interface is pretty underrated, though. Once you get the hang of it, it's very, very simple. The hard part is coming up with ideas!