Side bolted ball joints are nothing new Yello. Not mechanically perfect, but mechanically adequate for most applications
for an aileron that has what? 1kg of load on it? I think a short, fat,plastic servo control horn with a side mounted ball ain't going nowhere.
I doubt I could twist a 2mm thick control horn sized piece of prepreg with my hand...
The differential issue can be easily adjusted with end point adjustment in the radio, no biggie.