I had thought from reading previous postings (PPro CS4?, 2009?), that the transform effect was superior to using the motion (fixed effect), when upscaling video. I have found the exact opposite using Premiere Pro CS6.
I examined still images taken under the following conditions...
Project is DSLR 720p 60fps with edit>pref>default scale to frame size - enabled.
Sequence is 1080p 30fps upscaled to 150% and also 160%.
Frame captures were TIFF.
The 150% case is really a straight crop rather than an upscaling, (720x1.5=1080), but images scaled @160% showed the same degradation using the transform effect compared to the motion effect.
Has anyone else had similar results? Maybe under other conditions, upscaling using the transform effect, is actually best.