I'm just replying to this because I was posting on the
compost bins thread and saw that you all were looking for feedback on the tumblers.
My husband bought me one for Christmas this past year. (Being cheap, I probably wouldn't have bought it myself. hehe). And I started using it right away, even though they don't recommend you use it when the temperatures are so low. I'm in TN, (zone 6b-7a) and so we don't get nearly as cold as some of you, but it can get cold enough.
With the compost tumbler you are doing a hot compost, meaning, you are not doing it passively and adding materials slowly, but adding it all at once in the right conditions with the right amounts of nitrogen and carbon ratios to produce the right combinations of microrganisms that will heat it up to over 160 degrees.
I did start out with the right ratios and definately had some decompostion. I did accidently freeze my bin when I added some material with too much moisture on a really cold night. Even though I knew I wasn't going to get much action, I tried it anyway.
However, I have to tell you, the most amazing thing happened 2 days ago: We have had a week of 60-70 degree temps. and I opened my bin and it was steaming! I was SOOO excited! I put my hand over it and it did feel hot! It stayed hot for 2 days and then I even added more material (which technically is not a great idea as the process will have to start over again, but I don't really care at this point, because I'm not going to be using it for awhile anyway) and it was
still steaming after this. I admit, I was putting some effort into getting the right ratios and all, but, If you do it right and batch compost, meaning, add your materials all at once, it shouldn't be too much effort.
So, I'm optimistic about it. Even in February, with one week of 60+ daytime temperatures I am getting hot compost. That is promising. I can imagine that in the summer when it is consistantly warm, if a person does indeed watch carbon to nitrogen ratios, it should be very possible and simple to get compost in as little as 14 days.