Jarrod,
I have run a plain water drainback in cold upstate NY for over 2 years without problems. Yes, water is more efficient and less hassle vs glycol. For peace of mind I have 2 DeltaT controllers in series. Better one with display upstairs is on all the time, powering cheaper one when conditions are right. Both have independent thermocouples. My system is balanced so that when pump is on the water temperature difference is only about 15/20 degrees so never see high temp or steam in panels.
On a one story roof with Taco 009 in basement and with outlet of pump restricted with a 1/2 closed ball valve. Qty 2 4x8 panels and water flow low to keep from eroding the copper in elbows. Cutting back flow also lowers pump amps. Tank is 120 gallons. Works great for family of 3, 9 months of year. Back-up on a lot during Dec-Feb.
Anthony