Very happy I got the Chilling Package. It kept temp to + or - 1 degree.
I have had the cf5 for a while now. I tried using an upright freezer with a simple one stage temp controller. (The same kind that comes with the cooling package). It would over-shoot the temp by about 5-9 degrees too cold. Sure there are fixes, but these coils really do work!
I simply used frozen gallon water bottles in an ice chest and was able to maintain a lager temp at 50 with only swapping bottles once every 8-12 hours. I was able to "crash" to about 42 or so. Ambient temp was probably 75-80.
(Note- live in Northern California- I did not order the heater.)
Spike- here is my one gripe- the coils had printing on them out of the box. I had to soak them for about an hour in PBW and (carefully!) use a soft sponge to remove the ink. I don't know if the ink is dangerous or not, but I know I did not want it in my beer! Make sure you plan time to clean off the writing. Still a 5-star review however.