You'll have to let us know how it works, i've not heard of the cups working through the winter, in Minnesota anyways. Not sure how cold it gets where you are...Did you use horizontal nipples?Hi!
I've built my own bucket heater almost the same as this. The only exception is that I got the heater and pump on eBay from china for less than half the price. I also bought a "110V Digital Temperature Controller Thermostat" for $6 and set it for heating at 32 degrees F.
http://m.ebay.com/sch/i.html?_nkw=110v+temperature
I've also done the same setup with the pump hooked into my supply line for individual cage water nipples and cups. The supply line is a circle and returns the water to bucket, so it's always cycling. I wrapped the line with the black foam pipe insulation and kicked the temp upto about 36 degrees.
Thank OP!