I may have comparable weather, depending on where exactly you are in the mid-west.
I set my weep for the guns so it comes out the size of the lead in a pencil an does not fan-out...but fans-out a bit when trigger is pulled.
The foam brush can be set a little more volume, however since the orifices are larger it is less prone to freeze.
My weepmizer has two sensors attached (one in my attic and one on the north side of the building). The weepmizer will work off the coldest of the two...and having two gives you some sensor redundancy (if one fails, you don't freeze up). At 33F it will start pulsing. At about 10F I use the Weepmizers' second output to control a three way solenoid that switches to warm water. So basically you can weep more water when it gets colder or weep warm water. I chose warm water because if you weep too much, people will come in and wash with the weep.
Finally, make sure your weep solenoids are 'Normally Open' so if the power goes off, you don't freeze up. Yeah I know it sounds stupid, but mine were installed 'Normally Closed' until I noticed.
If you find freeze ups from time to time as you adjust things, you may want to buy a Thawing Machine. Something like this
http://www.pipethaw.com/ownersmanual.html If you use steel braided hoses for your Foam Brush and a steel brush head (instead of plastic), you can clip on to the pump (or top of the boom) and the other to the end of the brush or HP gun tip, wait a few minutes, voila! no longer frozen and the work required was very minimal (as I am lazy...I like that last part).
Good luck with your 1st winter!