I'm afraid I haven't had time to check in too frequently recently because my current project keeps me very occupied in Excel rather than the PSR or the forums! My expertise hardly competes with all the pros here! But I did check on this split point issue. The Accompaniment is always at the far left. You could, for example, set the Accompaniment split point at C1 so that the lowest octave on the keyboard is for accompaniment. If you set the Left-Hand split point at C2, then the Left voice would play ONLY in that 2nd octave. You could use the Sound Creator to set the bass voice an octave lower. So this would give you
C0 <-accompaniment-> C1 <-Left BASS-> C2 <- Right hand voices.
The 1st split point is the "A" split point and the 2nd would be the "L" split point. If you were to move that "A" further to the right, it would reduce the number of keys available for playing the left hand voice. Similarly, you could move the "L" accompaniment to the left and reduce the number of keys for the left voice. However, if you moved "A" all the way over to where "L" is so that the "A" and "L" split points were the same, THEN the accompaniment and the BASS would both play to the left of that single "combined" split point. If they are NOT the same key, that is there is a distance between the "A" and the "L", the left hand voice would only play in the interval between the "A" and the "L". So, you can set the keyboard up to have a left hand voice completely independent of the accompaniment area.