Any form of interpolation will degrade your footage. That's just the nature of the thing. What's not there is not there and upscale always looks "tacky" regardless of the chosen method.
I wasn't referring to the quality of the image when I said it looked tacky. I meant that the motion looked uncanny because the scale and position weren't synced. I came to the conclusion that like most things in After Effects, there is another method of creating an effect.
Two options. First option, if you want to zoom into a specific spot using scale then you should position the anchor point at the center of interest and then scale. The scale will have a bit of an unnatural feel unless you enable exponential scale (search for exponential scale in the Search Help field at the top right corner of AE to learn about that). The second option, make the layer 3D, add a camera, and animate the position and point of interest of the camera.
If you are going to zoom in or move in more than about 20% then I'd make the comp bigger, use detail preserving upscale to scale up the video, nest that comp in a standard sized comp, and do your move in the new comp.