In my recent post "Does English Need the Schwa?", I said the following:
Does a syllabic W (or schwa plus W) sound more like the vowel in know or the vowel in knew? I say both! (Bear with me, this is weird...) If the schwa-W is immediately preceded by a yod (as in value), it sounds like the word ew. If not (as in follow), it sounds like the word oh. So in cases where a yod sound would be systematically excluded from American pronunciation, you might hear the schwa-W as ew or oh, depending on whether the yod is there in the word's phonological representation.
This way of looking at thing has some explaining power. My daughter's first name is Julia, and people have a tendency to pronounce it as two syllables (/dZuwl.y@/). But what about the name Julio? No one makes it two syllables. (In fact, it's almost impossible for me to make it sound right that way.) They leave it something like /huw.l@y.@w/ because the last syllable of /huwl.y@w/ would sound like the word you. Think about it! It's a really weird pattern.
Well, I did think about it, and after a long while, I noticed the word jalapeno, which blew my whole theory (that part of it anyway). Using the standard American pronunciation of the word (if there is such a thing), the last syllable must begin with a yod. Yet, no one ever pronounces that syllable like the word you. But is that final syllable really stressless? I wonder.
Anyway, I adjusted my post, and the resulting theory is just a bit cleaner and simpler. That's nice.