SPI - Master and 2 Slaves (All PIC18F26K22)

Hi,
I am just playing with a project where I am using 3 PIC18F26K22 devices configured as a Master and 2 (Independent - separate select lines) Slaves.
All three processors have the PLL enabled so a base clock speed of 64 Mhz, hence 16 Mips (Not sure if this is relevant but thought I'd mention it)
Having contacted Microchip via a support 'ticket', only the Application notes and data sheets were implied.
My first question is really 'which method is best/fastest for data interchange between the processors - SPI or I2C ?)
Following that, if the answer is 'SPI', are there any 'members' who have implemented this configuration, and (if possible) any sample code in Assembler.
I'm just trying to 'short circuit' the coding process if anybody has already done it ... (Trying not to 're-invent' the wheel !!!)
Any help or advice would be appreciated.

SPI is faster by far.... I can do C routines but I haven't written any ASM routines for the Pic18...
I'm sure someone here has done some...

Many thanks for your reply Ian,
I thought it would be, but its nice to have confirmation.
(I really should bite the bullet and get into 'C' - I did do it many years ago, but have forgotten most of it now)
Most of my projects use small (Non 'C' compatible) devices with limited memory maps, so have to do some quite tight programming.
Roy

I would do a tutorial on the pic18... but I don't really have the time at the mo.... If no-one chips in, I'm afraid you may be writing one...