Received the first batch of PCBs just before the new year and managed to get some testing done. Turned out that while the breadboard design, with an PDIP part, rev 06 ran fine with an 8MHz SPI clock (for the SD), the PCB with a 44-pin TQFP, Rev07 did not. No idea why, but I just lowered the SPI clock to 2MHz.
9140100000