Compiling 4-RELEASE on 5-STABLE

[John Gillis]

	My apologies if this has already been asked. I'd like to upgrade
my non-production machines to 5.3 once it is released, however I'd like
the production servers to lag behind once I make sure everything is
working right.
	This might mean that my production servers would be running 4.x
for the next few months. Compiling world, the kernel, and ports is done on
non-production machines however, with the ports being packaged and
installed on the servers and /usr/src being NFS mounted from a
non-production machine.
	After installing 5.3 on the non-production machines, I'd like to
track the 4-RELEASEs into another directory, say /usr/src.4 while tracking
5.3-RELEASE in /usr/src.

	My question is.. would I be able to compile anything on 5.3 that
would still work on 4.10? Does the make build(world|kernel) bootstrap and
then use the /usr/src.4 development environment to link/compile
everything? Would I be at a loss with ports (not terribly important in my
environment)?
	Thanks,
		John