They still use one-bladers for FF. Mass ballanced with a lead weight... but dynamicly very unballanced. Bad idea for R/C.

Cubs will do more than some people think... A couple of years ago, there was a contestant at our club's annual Pattern contest who flew a Cub, and did fairly well.
You should have seen the full scale J-3 aerobatics demo at the old Byron "Strking Back" airshow appx 1994.... You see that, and you KNOW a Cub's not boring, even with less than 1:2 power:weight.