If you search on the TopBand Archives you will find numerous posts on the Folded Counterpoise, or FCP.
http://lists.contesting.com/archives//html/Topband/Discussions were, at times, heated. It appears that, especially for people handicapped by small lots, they made the difference between working 160 and having fun, or not. I don't recall any reports of rigorous comparisons of the FCP versus 120 radials, with field strength measurements. It doesn't amount to much money to build one up, and you can work off a step ladder to install one. It's worth a try, especially if you don't have 15,000 feet of wire and space to bury it.