Looks like it's a little too early to pop the champagne.
I thought the SHA-1 input was all constant except for the time\date\MAC address. On closer inspection, it looks like the 6th, 7th, and 8th 4-byte values also differ across DSes.
In no$gba: 3E031800 0000C331 0709BF16 (unscrambled 0018033E 31C30000 16BF0907)
In Desmume: 22062F00 00000000 05000006 (unscrambled 002F0622 00000000 06000005)
I know this is DS-specific because we get the same values regardless of which game I put in. This also explains why mattj and I couldn't get the same seed with the same date\time\MAC address way back when.
I really hope this is something we'll be able to find easily without an AR, like the Nintendo WFC ID.
EDIT, response to above: I get the same seed with completely different save files.