Regional variations in pronunciation

I've been thinking recently about whether I should adapt outlines to the way I actually pronounce words rather than the way the Simplified manual indicates.
I've already done it with 'schedule', which Brits pronounce 'shedule' rather than 'skedule'.
Now I'm wondering about the oo hook. In Lesson 22 of the Simplified manual, it says the hook is used to represent the sound in new, due, avenue, amuse, reduce and issue.
Now here's the problem: new, due, avenue and reduce I'd pronounce with the same u sound as amuse (as opposed to the American noo, doo, avenoo, and redooce - pardon the non-IPA rendering!). But no American would say amoose for amuse, would they? So I'm not the only one encountering inconsistency here.
But now a thought's just occurred to me: perhaps they were all pronounced with the same u sound as in amuse (with the exception of issue) in the 1950s, when the manual was written. I heard an old recording of Eleanor Roosevelt the other day, and I was struck by how 'English' she sounded, complete with 'yoo' instead of 'oo' sounds .
I suppose what I'm trying to do here is fix in my mind the outline for a sound, so I can write any word that has that sound. So if I encountered 'duty' for the first time ever, I'd either write 'd u t i' or 'd e u t i' without hesitation. The way I talk, the 'u' of 'duty' is the same as 'amuse'. So if I write 'd u t i' I'm writing something I'm not hearing. On the other hand, so are most Americans, as the 'd' and the 't' are virtually indistinguishable, so they're heading 'd u d i' but writing 'd u t i'.  (I remember a funny conversation I had once with a guy from Texas who was talking about a 'writer', but I heard 'rider'. I mentally imagined a cowboy, which was the last thing on his mind.)
There's the same problem with the aspirated w (while, whale, whether) which isn't aspirated on this side of the Atlantic any more, so I've been leaving off the dot.
What do you think? Should I just go with the flow and do what the manual says?

(by kevinwal for everyone)