Hi Jarlath!
Ketron modified sounds and styles in release 4 so if you use release 4 in the SD1Plus and release 3 in SD1 there are some differences.
I personally liked release 3 better so I stayed with it, I also never tried to move the styles and sounds between releases so unfortunately I can not help you much in this respect.
One of the solutions could be that you revert SD1Plus to the same release you have in SD1.
Best regards,
Luka