(Question withdrawn, I'm thinking about it some more.)

We will wait patiently!

Well, I reconsidered after I asked. I went back to the sizing charts and the difference in length was not one inch, as I first mis-remembered, but was only a half inch, which is how I ended up asking a kind of obvious question. I think I know the answer in that case -- maybe a little, not a whoIe lot. Could decrease the frequency of heel strikes on panniers some I guess. And it depends on the rider and what they're doing with the bike. Maybe a pro would notice?

I was just going to delete this thread but I didn't see how to do that. Maybe because I block Google JavaScript by default with NoScript, and since the site got reworked more of it seems to be relying on ajax.googleapis.com.

It's still weird to me that a frame would increase two inches in height but only a half inch in reach.

Reach is the horizontal distance from the BB to the top of the top tube. It doesn't say much of anything about clearance between heels and rear panniers; that's mostly a matter of a bicycle's chainstay length/rear-center.

About 13 millimeters.