How not to sell embedded Linux

I'd argue exactly the opposite.

if you need a trim, secure kernel with minimal features enabled, definantly track kernel.org.
with a minimal config it's far easier to test a new kernel and any security patches that come
out you can more easily apply (assuming that they are at all relavent to things that you have
turned on in your kernel)

it's when you want the 'everything and the kitchen sink, running on any available hardware'
that you want to think about backing off and running a distro provided kernel (so that they
can do a lot of the work maintaining it)