It is not that much of a difference, but to me it felt a little better especially under my right forearm. However there really should not be anything uncomfortable about it coming from the previous LUKE's and also from the reflex that you're playing now Dean. It's one hell of a guitar, and I think you would absolutely love it man.
Nice picture! Didnt see that one before. I can see the difference especially towards the back of the body. It looks a bit more elongated and not as compressed as the standard.
Here's a red standard Luke superimposed on a black HH LIII.
Not much in it. The LIII is a bit longer, less than an inch, maybe?, and the lower cutaway looks a little wider. Note the selector switch is moved lower on the LIII.
If you were to centre one body on top of the other, it looks like the LIII is 1/4 or 1/2 inch bigger all round. But with the same neck and scale length on both guitars, I've aligned the frets and bridge which are the common points between the two guitars.
Of course this is still kinda rough, not easy to find to photos that are taken from the exact same angle. And then you have to match the scale and whatnot. Don't take this as a perfect comparison.