HE-AAC ("High Efficiency") tunes

[Santa]

I'm hoping for a little advice.

I had my music encoded in vorbis (.ogg) before my move to iPhone land. I used 92 kb for my portable player and was quite pleased with the sound. When I moved to the iPhone I tried 92 kb, and it sounded a little off, so I encoded at 128 kb.

From what I've read, since v3.1, the iPhone (and iTunes) now support HE-AAC. So my questions:

1) Has anyone been listening to HE-AAC encoded tunes in their iPhone since the upgrade? Does it really play back at full quality?

2) Itunes limits encoding of HE to a max of 80 kb. If I encode outside of iTunes at a higher rate, will it play at full quality in the iPhone?

3) Any thoughts regarding relative quality of HE-AAC at 92 kb vs. Vorbis?

I did searches all over regarding this, and other than one short thread over at Hydrogenaudio I couldn't find anything.

Thanks