While I haven't seen the Hobbit yet, I was intrigued with using Pure Motion on my Optoma HD3300 after this discussion to see what 3D movies looked like. I tried Avatar and Titanic both in 3D, and I have to say the pure motion added a sense of realism I wasn't expecting. I've tried it on 2D movies in the past and didn't like the soap opera look--so forgot about it, but for 3D it added a clarity that made me want to watch Avatar all over again, and I've been bored by that movie in the past. It made the flying dragons come alive as it reduced the judder I normally see in fast motion scenes. I'm totally grateful that this discussion of 48fps led me to try something that I had completely forgotten about.
I have the same pj and I set Pure Motion to high on 3D blu rays. If I didn't, I don't think I could stand fast action scenes in 3D at all. I tried watching Tranformers 3 without it as the purist in me said I shouldn't use it. However, like you said, it makes 3D more watchable. I don't know if it's judder as much as it is 3D separation in fast action scenes that Pure Motion seems to allow my eyes to resolve better. At any rate, I keep it off for 2D and fully on in 3D and I love it. FWIW, the Hobbit is a fantastic film in 3D and really is how it is meant to be seen. I won't watch it any other way - it is that good.
Video: Optoma HD3300, Panamorph UH480, Darbee Darblet, Samsung BD D6700 Blu Ray player, DIY Seymour Centerstage XD 138" Curved Screen
LCR - Tannoy DC12i, Sides - Tannoy IW63, Rears - Tannoy Saturn DC6ti Bookshelf, Ceilings - Tannoy CMS 603DC (TF), Tannoy CMS 601DC (TR), 3 Micro Marty/1 Full Marty DIY subs
Amplification: Emotiva XPA-3, Emotiva XPA-2, Outlaw Audio 7700, 2x Inuke 6000DSP
Receiver: Anthem MRX 720