Thank you for the tutorial. I have not watched it all the way through yet though it looks promising. I have to say, I laughed at the remarks about storage space. My original solution was exporting HD from Premiere Pro and SD converting in After Effects - but I didn't have enough space ... so there I was, rendering a sequence in Premiere, converting in After Effects and once I converted a section I was DELETING the frames from Premiere Pro just to make room for the rest! Needless to say I bought a new drive over the weekend.
As you have found, the Scaling algorithms in PrPro are not the best around. Jeff's method is very good. Some others will use AE for the down-scaling, and some use other programs for the encoding/transcoding. This is probably one area that Adobe should be looking to improve on.
Note: the same quality issues occur with over-sized still images and Scaling. For those, we recommend doing the resizing in Photoshop first, as the Scaling algorithms are better, and that program offers much more control on which one to use.
Good luck, and enjoy Jeff's tutorials,