lefty, do you know if avrdude was built by Atmel as part of an official tool set, or something
jinned up by freaks? If by Atmel, one might think they would have proofed it on their larger chips,
and it would be 100%. Microchip's tools like MPLAB are continually updated to reflect their newer
chips.
There's a problem related to a bug inside the GNU avr-gcc compiler. If I remember well, the compiler cannot create code that can directly access data in FLASH is it is stored over the 64 kB limit. Latest versions of avr-gcc aren't affected by this bug, the one that is included with the Ardino IDE is.
You can upgrade the Avr toolchain to fix it. I did it for my Linux box.
leo, have you tried uploading files > 64KB to your boards, and had the programs run successfully?