Andy , the CP3020 is a sheet feed dye sub, as good as it is as a machine , it is slower than a roll feed, and the price per print is higher. Most event guys use roll feeds, for speed and cost.
The nearest equivalent to the 3020 is the Mitsubihi CP3800, which is very simlar to teh DNP DS80.
If you do a larger size print , you wil have to charge the going rate , which wil be approx £15-20. Most event guys in the UK charge £10 for a 6x9, in a mount.