There is a forum like Signs101 in Germany ( in german language) for professionals, and they did a survey a few weeks ago which plotters are in use day by day at the sign shops. 121 Members have voted, and the results are:
Summa 54%
Mimaki 24%
Graphtec 12%
Roland 4%
GCC 1%
Others 5%
If comparing tracking accuracy and repeatability, Summa is with up to 12m on a S-Class with media up to 760mm width the best I have found on the market. The OPOS X-System is with special functionality like OPOS XY, OPOS XY2, OPOS BARCODE, OPOS SHEET MODE, OPOS PANNELING and so on for my opinion the most functional contour cutting system on a roll plotter. For example, if comparing speed even of the regular OPOS (not CAM) with the contour cutting system on a Roland, the difference is significant. With up to 128 markers, OPOS could find and compensate deviations which other cutters with only four markers can't recognize.
One time a customer (we are dealers) comes to our shop to have a look on a latex printer to buy. He have told us that he owns a Graphtec which is nearly new, and so he doesn't need a contour cutting plotter to his latex ... after the demonstration he trades-in his Graphtec and orders a S-Class 2.
I have seen one time a comparison of the Graphtec FC8000 and the Summa S-Class 2: the Summa is faster with regular Cut only and Print & Cut (up to 60%), for perforation cut the Graphtec knife holder position needs to be changed by the user, what is not needed when using an S-Class and so on. For power users, together with OPOS BARCODE, Contour cutting of multiple jobs on a roll can be carried out completely automatically.