I dunno, but I write my uppercase Gs like those ones up there. (I copied to from my mom, grandparents, etc.) My last name starts with a G, so I use it a lot. (I don't like the normal cursive G they teach now—it looks ugly.)
I still remember annoying elementary school cursive teachers by refusing to write capital G the D'Nealian way.
Now that I think about it, I write a lot of my capital letters differently from standard English cursive. In general I hate it when capital letters are simply a larger version of the lowercase letters—especially when the printed form looks different.
a, m, n, u, w, y, z are prime culprits - I write all except u and y in a different way. (I can't think of a good way to write u and y in a different way. Any ideas anyone?)
Another cursive capital letter I don't like is E. I like my Es to have at least some sort of blockiness to it, not completely round like in D'Nealian—it looks like a lower case epsilon—ah, that might be why I don't like it, it goes with my other no capital should be a bigger version of a lowercase rule (Some people write their lowercase 'e's to look like epsilons). I usually end up writing my Es in a different way each time when I have to write them, and try to avoid the D'Nealian E.
M I haven't fully decided on yet either. Right now I write it like a handwritten lowercase mu, but if there was a better way to do it I'd be glad to know.