>>>I didn't know exactly where I would be be right... it's a Heisenbug.
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>>One philologist was just the other day explaining to me why both are OK but have different meanings - my being the one that still holds, yours being one that held at the time when the sentence happened. But he's in Toronto... any substance in what he says?
>
>I had to look up what a philologist is. Maybe both are right for different meanings but I can't see it. "I don't know exactly where I'll be" sounds right.
>
>You could think of my version as "I didn't know exactly where I would be be [being]"

OK, found it. Here's what the guy says:

"She said she would come" - means that her arrival may be in the past already; it was in the future at the time. ""She said she will come" - means the arrival has definitely not occurred yet.

"She said Niagara Falls is an ugly little town" implies a permanent truth, was valid then, is valid now; "She said Niagara Falls was an ugly little town" leaves a possibility that something has changed meanwhile (i.e. nuclear bomb fell on Clifton Hill), so we only know for sure that it was true at the time.