Not sure why the roll==banner fixed the problem, but I have always had concerns when making larger prints with the Epson
Your problem on the cut off more than likely comes down to either the printer driver, or LR spooling the job. As Jim pointed out, you can
test the Spooling of the job correctly by looking at the "print preview window". If the image shown there is full then the job being sent to the
printer is correct. The print preview button in on the last screen before you hit print. I agree that it's always a good thing to check it.
If the job shows correctly in the preview but you still get the printer cutting it off short, then it's more than likely something in the printer since
the job has been spooled up correctly. This could be many things, network connection, USB cable, PC (or Mac). One thing I will often due is
under printer preferences I will tell the print to send the job in raw format. This seems to help on longer jobs.
On my system, I recently ran into just the opposite problem. On a 35" x 85" print, when I printed from CS3 or CS5 when I viewed the print in the
print preview I only had about the 1st 50" of the print showing, however the print preview displayed the entire page size (in this case 89" long which
was a custom page size I had created). I knew from past experience that I would get just that, 50" of image and then the printer would advance the rest
of the canvas to the end of the page leaving white space. Nothing I did could fix this, reloaded the printer driver, reconfigured the prints, etc. However by
printing from LR4, I was able to get a good print preview which displayed the entire image correctly and the corresponding print looked fine. So
for that job I was glad to have LR4 installed.
That yours worked correctly with banner is surprising and something I will keep in mind for my next large print that displays incorrectly.