Johns Daniel wrote:

Is it possible -- and prudent -- to use a single kernel binary image
for two similar boards, one based on an e300 core and the other on an
e500v2 core?

No, it is not possible.  They use different MMUs, and the kernel does 
not support choosing between them at runtime.

I was surprised to see that the e500v2-targeted toolchain did build
the kernel for the e300 board just fine. Don't know whether this will
always be true?

"always" is a strong word, but it should generally work.

-Scott