MD I did the same test over the Summer and I got the same results as you. Im thinking mabey as the #11's have less charge as the 209's, thus more fouling as the 209's burn the powder better? I did the same test with various 209's also, and with them too some had more fouling and some were more and less accurate. Go with what works best for you.
Anyway good to be back on the Forum and I wish Everyone a Safe and Happy Hunting Season 2009
Ron