Ive used the Hennessy expedition hammock. get em at MEC
They are good stuff, but there is no way id be in there if it was around -10c. The problem with the hammocks is they allow easy air flow all around your body, as your obivously off the ground. Benefits would be that they set up in a matter of minutes and there is nothing as cool as staring at stars from your hanging bed in the summer time out camping. To keep em warmer you can throw in a camping air mattress in the bottom...
You should look into getting yourself a single man tent...
http://www.mec.ca/Products/product_detail....845524442629299