I'm now running B7 T5 F9 and the car runs like an S.O.B.
I have had the RS4 valve fitted for a few months now and have also had the Forge K04 actuator fitted.
The Actuator took a fair bit of setting up, but now it is settled in it runs just great.
The RS4 valve ensures that the actual meets requested. Like others have already said, my car failed to meet requested between 0 and 5 bar, which could give issues with how the car runs (although I haven't felt anything).
The side effect of fitting the valve is that it helps with the low pressure in-tank pump. I found during logging that before the RS4 valve was fitted my in-tank pressure was dropping down to 3.5bar, which would affect it's ability to back up the high pressure rail system. Now the valve is fitted it doesn't drop below 3.9, so it has the ability to back-up the rail system faster.