EnderMyst,
I haven't changed the coolant yet on the Xterra, but every other system I've worked on was similar...having the lower radiator hose/radiator drain lower than the lowest cooling channel. Sure, there's a potential for some coolant to be left in the block, but I don't think it would be much...

You do have a good point on measuring things, heh, I'll see if I remember to do that when I get around to swapping this fluid out.

Bogatyr