I'm playing a lot of notes at a time usually - probably 4 in each hand - so you can't hear too much of the rhythm anyway. I tend to stick to one variation (A). The fills on the PSR740 (at least in the styles I use) are two bars long so probably on the last chorus I trigger the C variation two bars before the start of the chorus so I'm back in the regular rhythm as the last chorus starts. Bit old-fashioned I know but then I'm an old square. So I am an almost worse but not quite.

Bryan