The pizza wheels only come down at the end of printing a sheet but they engage the surface of the print about 6 inches from the end of the paper. On my paper of choice, H Photo Rag Baryta, they are clearly visible in the printed area (with bright light at a severe angle), thus marring the print. They seem to be there to eject the paper. There are two separate sequences of these pizza or star wheels. The first seems to dig into the print to move it into place for the second set of pizza wheels that move the paper along until its completely ejected from the machine. This is different from the 4xxx series printers where there is only one set of pizza wheels (but two rows of them). You can see this happening as you look into the printerís paper path from the front. After it ejects the paper, it then retracts the plate back out of the way so that the pizza wheels don't affect the entire sheet. This happens on every sheet.
As for the H Photo Rag Baryta sheet handling problems on the larger series printers, my only experience is in working with a local professional lab. They've had problems with thicker papers feeding using the sheet feeder. The platen was set at the "wider" setting. Some sheets would load fine; others would not feed at all unless pushed a bit from the top. Neither of us could come up with a procedure or setting that solved this problem other than using the push method. There may also be variances in the manufacturing of each machine, particularly if others aren't experiencing this problem with H Photo Rag Baryta. Thinner papers work fine.