Is Extra Sensor Worth It/Needed?

[CodeSection]

I'm setting up a two vessel RIMS system using one 5500W heating element similar to the BrewEasy system except my kettles will be side-by-side.  I will be using two pumps and will be circulating between themselves as well as each other at different times.

The controller will also have two pump controls and one sensor will be installed in a tee on the BK's outlet valve at the bottom of the kettle.  I learned that I can add a second sensor (that will report to a separate DSPR120) to the controller.  I'm not sure what the true benefit would be to have two sensors (one on each kettle installed on each of the output valves at the bottom) since there will only be one heating element.  The heating element will be located in the BK.

Is it worth getting the extra sensor to be attached to the MT's bottom valve just to monitor that tempt?  The BK will have a sensor at its bottom valve.  Plus, both kettles will have a dial thermometer.  Is the extra sensor overkill?  I would imagine the manual thermometers will read differently just because of their location.  So, I guess they would only be a reference that really will not be relied upon.

Would a second sensor give a more precise reading that will make a difference on how and when to adjust the BK's heating element?  Or, will the BK's sensor along with the manual thermometer on the MK side be sufficient?
 
Thanks for your help!   

[brewfun]

In most cases, you won't need another temperature probe.

The second sensor could monitor temperature just after the element and have a high value switch off function. If the wort exceeds a certain temperature, the controller would lower the element temperature, cycle it or shut it off entirely.

In most RIMS systems, the flow rate seldom lets the wort temperature exceed 10^oF above the incoming wort temp. Yet, if you have issues with stuck mashes then slowing the flow is the best answer and that could lead to temperatures exceeding 175^oF. In that case, you'd want to know when you're near temperatures that denature enzymes.