CS4 wasn't very good at it, which is why Dan developed that script. Things got much better starting with CS5 and PP now produces very good results, especially with hardware acceleration.
Would you recommend using MRQ in for this purpose or it will be just a waste of time.
With hardware acceleration, you don't need it. Without hardware acceleration, I'd leave it on.
It's been awhile, but last time I did this (last fall, using CS5) I just exported from Encore to DVD. I spent so much time futzing around with getting the menus to run the way I wanted that I've forgotten exactly how the 1080p30 source got downsampled -- I think Encore used AME to do it. In any case some Adboe software did it; I didn't apply anyone's workarounds or tweeks. The resulting DVD quality was really pretty good. And when played in a blu-ray player, it upsampled surprisingly well. Not blu-ray quality, but better than some standard DVDs I've watched on this same setup. And the client tells me that DVD is still selling for her, so it must not be too bad ;-)
This from CS5. I expect CS6 to be better, and I'll know for sure next month because I'm editing a project now that finishes as a set of DVDs from Encore.
As to export time, IIRC it took on the order of 3-4x time to export (so a one hour vid. took 3-4 hours to export). I made something like 20-30 motion lower thirds in AE (dynamically linked from PPro) and did all my color correction in AE using the Color Finese plug in, so AE was called in extensively during the export. I don't feel badly about those export times.