honestly speaking, the units in demo rooms are always being used for demos, tests, engineers, sales reps, analysts, technicians, customers, etc ... it probably didn't have a tune up before you saw it. Demo units are always used beyond their limits; I don't think is unique to Xerox.
On the Xerox side though, you can ask your Xerox representative to provide you with the Xerox 4112 Customer Expectation Document. You will have in writing all the specifications of the machine, including front to back registration. If you buy a machine that does not perform as expected (as written in the document), you have the right to call Xerox as many times as you want to make any necessary fixes until it is under specs; if they can't fix it, they would probably replace it by the Xerox Total Satisfaction Guarantee :
Total Satisfaction Guarantee
