“Faster, maybe. Quality, not so much. Adobe Media Encoder’s deinterlacing and scaling quality is downright abysmal. “
We had some of these issues in past versions for certain presets, but have worked hard on improving the overall quality, so I think it fair to say give CS5 a try before you give up on the quality aspect of it. Also, as with any encoding product, a lot depends on the actual settings. For example, I know that some people make the same comments about Compressor, but a buddy of mine sells a set of hundreds of Compressor presets to help address a lot of those problems.
Good luck either way.