I have one and I control the flow there if I need to. So far (2-3 brews) I have not needed to worry too much about the flow, run it a WFO (wide fricken open). I do however control the flow when I fly sparge- but there I am controlling at both the inlet for the autosparge and the outlet of the MLT (kind of defeats the purpose, but nice to have a checkpoint with the autosparge if I get distracted when I am sparging).
Here is video of my rig:
http://www.youtube.com/watch?v=_Bqw1x4vXDM
I have since added another pump and did a bit of "reorg" with the pumps and such...added SS camlocks on everything as well. I am thinking my last little bit of change will be to add an inlet setup on the brew kettle as so I don't have to flop a hose in there...make it a bit more clean.
Hope the video helps a bit...new video forthcoming here in a week or two.