As I said, the features sounds great. But except of the weight for me the body of the S1R was near to perfect! I never had a camera before with such a good handling (my personal impression) and the S5 body comes near, but is not as good as the S1 type body. Only the weight of the S1 bodies is really bad…
I understand you like the S1R body, and I understand why you like it. I'm not trying to deny your feelings. But I feel the exact opposite - the S1R is not just too heavy, it's far too big for me. Too big to hold, too big to shoot comfortably. I dislike it at least as much as you like it.
But I think we both agree the features and performance qualify it as a flagship camera, right? "S1" is Panasonic's label for their flagship line. Denying it that label just because of the size is flat-out wrong. "S5" is Panasonic's lower-end line, and calling it an S5 just because it's smaller is misleading.
But this is personal and would be different with anyone from us…
I admit this is a personal sore point for me. I feel I've been under siege for at least a decade, since the Lumix GM5. That was a near-perfect camera to me at the time; fit in the palm of your hand, could take it anywhere (including a lot of places that were 'no big rigs allowed'), but with a premium build, a viewfinder, and enough manual controls for my style of shooting, while taking pictures that were just as good as its contemporary M4/3 siblings. But it was constantly derided as a 'toy' camera, by people who insisted that
real cameras had dozens of manual controls and switches and had to weigh 15 pounds. And it died, because it wasn't given a fair shake.
The decade since hasn't been any kinder. Other cameras I loved for their size and premium build, like the Oly Pen-F, got similarly criticized as "fashion" cameras not worthy of serious photographers. The size of flagship cameras like the E-M1 series kept creeping upward.
So when I see someone saying that a camera doesn't deserve the flagship label because it's smaller, that punches my buttons.