What prevents this method being used with other 'A' series cameras and the TX1 ?
Nothing prevents, any VxWorks camera can be added (now supported A550, A560, A570, A630, A640, A710, G7, S3IS and even IXUS700). But writing mount.c in assembly for each firmware is exhausting work
For old cameras without SDHC support multipartition boot is not too useful feature (any SD card can be formatted as FAT16). For IXUS700 this is made due to very low FAT16 performance on this camera at reading directory content (list of 200 files CHDK can read during 1-2 minutes!), FAT32 on this camera is pretty fast.
