Can any device run at 100% indefinitely? Any weaknesses the PSU might have will make themselves known.
If it's flawlessly built doesn't suffer from inadequate ventilation, I don't see why it would not.
The FSP-manufacured Be-Quiet! e9 700W PSU
is a four rail
device, meaning you will have to figure out how best to wire your cards. One of those rails will feed the CPU, the manual or manufacturer's specifications should tell you which one. Use the remaining rails for feeding GPUs.
The the OCP protection chip overseeing those rails is configured to trigger at 18A (216W), 18A, 22A and 22A (264W) but of course you can't apply such load to all rails without seriously overloading the PSU.
Remember that it's not prudent to run close to 100% load - should AMD screw up the next driver version and reintroduce some flavor of the infamous CPU bug, the CPU will require additional power possibly overloading the PSU.
The same goes for underclocked memory/undervolted core - should you lose your configuration (e.g. while testing another miner) the power usage of the whole rig might rise.
I use a kill-a-watt clone to make sure I don't run any rig at over 80-90% load capacity for this very reason.