I also get poor motion from blu ray, I have tried PS3, Samsung 5900 (VERY, VERY POOR!!!), and Panasonic DMP-BDT310 , the BDT310 being the best. But DVD plays soooo much smoother than blu ray, to the point I have sold my blu ray films. The upscaled DVD images are stunning, but then I view from just over 4 meters away so can afford a little noise with out noticing, I have never seen any tho as I walk past the set to answer the door, or stand closer to play guitar hero (sorry). I use a Onkio 608 amp and pass images through unmolested, but it still alters images from 24 bit to 30 bit, not sure how to stop it doing that either!
The only blu ray films I now watch are Avatar, because oddly it suffers none of the motion problems other films display yet has stunning colour and depth, and a few 3D titles, lete be honest the whole 3D thing is a pure gimic and I for one dont expect a lot from the experience. Its nice as a novalty now and then with a few mates around and a take away.
Shame it has come to this, the audio on blu ray disks is a noticable improvement over DVD, but the poor motion drives me crazy.
Also, I have some very costly HDMI leads that a friend gave me (he is an AV engineer and recomended them) but I for one can't say they fair any better than the £2.50 eBay ones, the eBay ones being 0.3 and 0.4 meters making the install behind my AV rack VERY neat, and must reduce induced signal noise as there is less conductor length crossing the magnetic path of other conductors i.e. power cables (I also trim power leads short to keep the install neat and reduce the magnetic flux produced by current carrying conductors). I cant proove this helps, I havent even noticed a difference, but the theory is solid enough.