Hey Mark--
Yes, in my wife's office we've got the M3s upside down. They are on the bottom shelf of an elfa hanging shelf system, with about 4" behind them.
Because the shelf is above head height when she's sitting at her desk we tried the speakers right-side up and upside down. This is not a nearfield listening set up, so not identical to yours. But our preference (or at least mine since my wife didn't really seem to notice much of a difference) was upside down.
So there you go. Does your office suck as badly as your HT room?
Take care,
Rich
