There is a way around it. By abusing the onion skinning, you can just set the layers so that you have a transparency colour and each layer is 100% visible. this way you can set up as many layers as you want, but they are not as dynamic as normal layers and not really seperate. all it does is that it shows the frame underneath or above, whatever distance you want. ace for animation and i abuse it a lot for other things.
and yeh 6 will have layers.