Sorry about that. I think everyone does it (and misses that point) because there is no physical connection to those pins (apparently, since it uses the ICSP header). When the Ethershield is covering the other pins it makes sense that some would be used. On a related note, all the tutorials mention ports 11-13 but nothing about the differences for the Mega. Ignorance is not an excuse though... and the tutorials have to be written with SOME basis of understanding.
Thanks again for the information. That of course solved it.