You'll be surprised how quickly you'll get used to the weight for hand-held work. I regularly used the shift lens (over1kg) on my ProII with the AE Finder and WinderII when shooting cityscapes and occasionally compounded this by switching from a 220 back to a Hasselblad digital back which is quite an additional weight. For a couple of hours, it's still fine but beyond that you can serious neck ache!

I've just added a Fuji GX680 II to my gear - and suddenly, hand-holding the RZ is a joy by comparison!