I sold an attorney an HPz6100 - (think that was the model #) about 2 years ago. We went with the 60 inch model which is solid.
Took out OCe who had a system there on demo for a month but couldn't close the deal. I literally waked into the deal. Hp supplies are not that expensive but there is an area to make more cash on the paper side.
There is a myth about the CANON Plotters passing on a nasty odor - like old French Fries when they warm up. I can say that people who buy these don't like to stray away too much from the manufactures they know and trust - even if you are cross selling to a client.
Keep me posted on how this goes.