Evening wood green wonderboy, I keep forgetting its a bit milder down here when I offer my ideas.
Sundance, the yellow one, grows well down here. It's a funny thing but I have, over the years, realised plants need to acclimatise to certain areas before they begin to grow well. Often my,own cuttings make better shrubs than the parent bought elsewhere and the yellow choisya is an example of this. My original plant bought from my local GC ...but produced "up country" .....struggled to grow. Cuttings I took from it produced far stronger plants.
However, I do think if a plant is more trouble than it's worth then its better to grow something else. Nothing worse in the garden than a sickly looking plant