I would suggest you think about the lightweight FS5 with a decent bit of heavy glass hanging off the front and consider whether that is in any way an advantage? If you're only going to put Sony's flimsy E Mount lenses on an FS5 it'll be fine but put a 24-70 F2.8 on it and it'll be so front heavy hand held shooting will be uncomfortable to say the least.
I think you'll more than get €900 extra value out of the additional features of the FS7 and you can shoulder mount it without any rigging if you rig the VF much further forward which you can't do with the FS5 which is aimed squarely at hand held shooting out of the box.
The FS7 rolling shutter is certainly adequate but not the fastest around, I rather doubt it'll be any issue for you unless you shoot like a whirling dervish.
In fact we are going to use - whatever camera we decide to invest on - with our Zeiss glass plus 2 Sigma zooms (18-35 and 150-600)
There are good deals on used FS7s beginning to appear too
http://www.reduser.net/forum/showth...7-package-for-almost-loosing-2500-(crazy-deal!!!!)
buying second hand will be difficult since we are budgeting the whole project for financing. Anyway, a new one will end almost at the same price that guy is selling his, since we are going to deduct VAT charges on all the gear we are going to buy.