Thanks Mike,
they are all 7k voices bar one backing voice from EW01, but looking through the menus the 7k has a very similar voice available, so the same could be achieved from 7k alone in this instance.
As for time, getting 2 measures of one track from a midi file into a composer track took about 30 seconds
It probably took about 2 working days, since I had no score and had to listen to the original songs a few times to play suitable backings into the composer. In fact I made several mistakes by putting some transitional measures at the end of composers instead of in fills, which would have been easier to play in, but by the time I had got the feel right it would have been more work to go back and change it.
I work two steps forward, one step back - making a very full version, then coming back a day later with a fresh perspective and thinning everything out to get just the basics which make the impact. Just because you have 8+2 backing tracks does not necessarily mean you need them all at once
I then sent it to a very good musician friend who listened and suggested a superior chord change, which worked better, so I just easy recorded again with the new chord progression.