I also downloaded the test build and did a lot of testing... unfortunately could not find any combos that allowed me to do 1080p 60fps with an acceptable quality. The "taking too long to encode" issue goes away but at that point I may have been running into a cpu limit on my transcoder (it's just the i5 2500k). I found it rather difficult to tell whether a problem was because of the transcoder or the quicksync...
Thanks everyone for chiming in with your results, good to know it wasn't just me.
Thanks everyone for chiming in with your results, good to know it wasn't just me.