> If you don't mind doing a "make clean" from the top level before building 
> for one of your architectures, mounting the source read/write isn't a 
> problem.  I've done the same thing to share between my mac and i386 
> systems.
> 
> -bob

This is may be ok for you.
But ...
Do you know how long it takes to make a full build from scratch
on a Decstation 5000/200 :-(
This counts in days - not in hours!

Andreas