I've seen straightflushes being laid down to higher ones before.
The title of the thread is "Huge Laydowns" and you implied such.

When there's a straight flush on the table.

6789Td on the board, $200 in the pot, and a $200 AI in front of you. The guy had the Ad, but that's obviously redundant. Granted, it's a bit different since he's only calling to chop, but he still technically laid down a straight flush.

I'd hardly consider this a huge laydown. That's like saying you laid down quads, but the board was 7777J and you didn't have an A.