Yep, it was (I'd put the wrong mainmenu5.xip in the new setup's test directory) eh!

Moving on, here are my test results...
The HDD version of the '5680' dash...
(i) displays normally with both retail font files in the fonts directory;
(ii) displays only a feint webbing background if they're not (including when only one of the retail font files is in the fonts directory) and then hangs;
(iii) displays normally with no font files in the fonts directory but with both retail font files in the root directory;
(iv) displays only the feint webbing background if they're not (including when only one of the retail font files is in the root directory) and then hangs.
This suggests to me that it's not font exploitable, as it seems to require both retail font files (but I realize that it doesn't prove that) eh.
