Chris,
I put a few pics of my frame in my gallery, you can check them out there. Sorry, but I don't have any of the round tube chassis.
A round tube chassis is "supposedly" stronger than an equivalent wall thickness rect tube. I
guarantee that you will not have to worry about strength in this chassis.
As Bob pointed out to me, the rect tube is a little easier to add brackets, bolt holes, etc to mount various hardware. It has turned out handier I'd say.
I visited both Shell Valley and Midstates before I decided (an easier thing to do these days...
) and thought that the Midstates looked like a stronger chassis - the SV seemed just fine but the MS met the "eyeball" test.
I'm biased, but I'd buy the rect tube from Midstates....