I handhold my RZ all the time, have shot probably 80 rolls with it so far in the last few months, none of which were on a tripod. So don't bother telling me what you think about handholdability. I've been there and done that.
Try handholding it for sports shooting with the 350 apo with hood, prism, Lgrip, motor drive and 350 bracket. Let me know how that goes.
It's doable, but not for long periods, like all day. It's not just the weight, but the ergonomics don't really help either.
Agreed though about the limiting apertures. Having the fastest long lenses be 5.6 is a real pain in the ass when trying to shoot 1/400 with 100 ISO film. I wish the 350 APO was an f/4 lens.