Hi russed,
Good idea, I use grub a lot like you to boot some small iso and where the speed is not an issue.
But if I remember this right, th cd/DVD emulation done by grub uses heavily the the bios for disk accesses
which is quite slow and may create problems on older systems with large disk sizes (especially if the iso
is located at the end of the disk) I am also not sure how the Linux kernel handle shared data (or can coexist)
with the grub/bios routines. For this reason I much prefer to rely only on the Linux kernel and only
use grub for the bootstrap. That being said, I am glad that this option works for you.
My two cents,
Gilles