The Sonic bar really takes some getting used to - specifically the sheet in / sheet out cleat.
I really don't like the inability to adjust it on the fly - especially in high winds when you need it the most.
Of course it does need some getting used to as it is different .... however, you can adjust it on the fly most of the time with practise.
If you find it hard when really powered its not like you can't use the sheeting to cope until you can get into a position to do it.
One easy way when powered is to let go the bar, then you can adjust the sheeting at the cleat ... then easily get the bar back while the kite is still in the air.
You could also bring the kite down and let go ... then adjust the sheeting and re-launch the kite from its tip at the edge.
I don't find it a problem and don't need to adjust my 11m much at all now I have it more and more dialled.