I've added the additional cap pads to my design but I can always jumper them out for testing on the prototype boards.
One thing I am doing is setting a 28 pin DIL socket inside my 40 pin one, with some approrpiate 328P pins joined through to 1284pins. This lets me use a 328P on the same board if I don't need all the peripherals or FLASH/SRAM of the 1284P/644P.
On the 1284P the 2 pins used for Channel 1 & 2 (8 Bit Stereo Full Rate) don't clash with anything else. On the 328P Channel 2 is Pin 10, clashing with SPI hardware SS.
I saw the wiring.c patch for the timers, saying that pin 6 & 5 can be used to get 16 bit stereo at half rate. What I would like to do, is use 6 & 5 instead of 9 & 10 for the default 8 bit stereo. Is this possible? I tried making a few changes to the defs file but realised it needs some of the hardware timer definitions altering too if it is possible to make it work.
If possible then It would be ideal if there was a setup parameter to use the alternate pins IF the patch is applied. I'm sure this would be useful for 328 users who want 8 bit stereo but use Ethernet shields or other SPI devices.