One thing working in the Customer Service industry taught me was that you only hear from the people with problems.
If the Cow isn’t full of threads cheering the release to the sky, don’t assume nobody likes it. The people who haven’t run into problems aren’t posting here for the most part – they’re busy cutting footage.
What’s interesting is that Apple provide an intermediate vector programming library so that you don’t have to write “bare metal” code for each chipset.
If the Quad genuinely can’t keep up (I’ve yet to see anyone confirm it can’t), then it would appear that Apple didn’t use it’s own libraries and wrote SSE3 optimized code exclusively. That’s a little lazy in my opinion.
I’ll just add another vote for the Compressor route. Exported a 1080i50 short yesterday to PAL HQ DVD and Dolby Stereo and was very impressed with the encode. Drag and drop into DVD Studio and you’re good to go.