Zune Thoughts: What Video Format and Bit Rate Do you Use on Your Zune?

I was doing a little experiment today with my Zune: I ripped a single chapter from a DVD, using CloneDVD Mobile [Affiliate], and I used their .mp4 preset. The program helpfully allows me to specify resolution and bit rate, so I wanted to see the ceiling the Zune had on bit rate. Ripping to 320 x 240 in resolution, I ripped three different files at 500 kbps, 1000 kbps, and 1500 kbps. The Zune 80 could play all three of - I knew it could handle the first two, but I wasn't sure if the processor could decode 1500 kbps MP4 files. At 320 x 240, 1500 kbps is probably overkill (I think 1000 kbps looks identical), but if you're ripping to 640 x 480 to play back on a TV, the more bits the better. I haven't tested the upper limits of the Zune - I'm not actually sure what the threshold is for when the Zune desktop software transcoding kicks in. Anyone done any tests to find what the upper limit is for Zune video quality? What Video Format and Bit Rate Do you Use on Your Zune?