One other thing to consider
is what their definition of "Heavily modified" is. Are they just recompiling the kernel with a completely different set of options (through 'make menuconfig') and maybe compiling in some hardware specific code (such as for an nVidia card), or are they actually replacing major parts of the base code?
~~~)-Steven----
"I want you to remember that no bastard ever won a war by dying for his country.
He won it by making the other poor dumb bastard die for his country..."
General George S. Patton