Hi Dustin,
I'd like to see, hear and do more on this question myself.
A problem I see is that there are tons of variables.
Historically speaking, we can assume that the two are not in a judical duel as they are armed differently. So that brings in the consideration of the surroundings of the battlefield.
Another consideration that changes the variables is the size of the shield and whether is it strapped or a center grip.
I think the center grip allows the S&S to quickly drop it and transition into the close fight.
If strapped, the shield can be used to attack even your armored enemy as you can bash with the rim. A sound bash to the head will disrupt even and armored opponent - the mass can be significant so I don't think it can be written off too quickly. The shield is not as maneuverable as a buckler but it shold be considered a maneuverable weapon, I think.
I don't think that any element of the fight will be that easy. Both weapon systems have huge advantages of different sorts... and nothing says you cant half sword a shorter sword, too... I just lots of room for all sorts of fascinating and 'unpleasant occurences' in that fight!
If we are talking about a battlefield then there is the secondary weapon consideration.. Long sword closing on the S&S guy after displacing the S&S sword.. the S&S can drop sword and draw a dagger (behind his shield-) as the close takes place... in the bind drop the shield and grapple...
So many variables but it would be extremely enlightening to work them out (and fun, too). I just don't think that it would necessarily be that easy.
I predict that there will be no 'perfect technique' that nullifies the S&S via the long sword, because the Martial Artist and the circumstances will always weigh too heavily on the fight. I just think that if both are skilled, it just is not that easy.
Plus, for every technique, there is a counter...
I am looking forward to see what comes out of your discussions there and the continous woring on this idea in the 'field'.
Sorry for rambling a bit.
Thanks,
Tim Sheetz