Hi Wightstuff,
You can quite easily use a flow control valve with your pump, whether you have a varistream or not. We use 60 and 100psi flojet pumps and have been using them for 5 years now, we have always used flow control valves on the poles(as stocked on our site) and we have never burnt out a pressure switch (which is the part that is worked when using a valve) we have after 3 years managed to simply wear out a motor with constant use though! I do not know how long a Shurflo would last , I have heard of tales of them only lasting a year or so, which is why we don't use them.
Alex