I'm not an expert in this area really. I've heard the argument made that even if static IP's were commonplace you would still need other fingerprinting methods as there are entire houses/apartment complexes/businesses running multiple users through NAT behind their static IP.

Also, I'm not sure what your experience has been but my IP only changes very rarely. Seems to happen about once every 6 months. My understanding that this was somewhat common, at least in the land of cable/coax-ISPs. Is 6 months not long enough to glean anything useful?