What to replace Canon 6000?

we are nearing the end of our lease on a Canon 6000 - we are a small commercial printer, average 70M clicks a month. mostly 12x18 cover stock, lots of duplexing. we have had so many problems with canon service and so much down time on machine that I can't bring myself to sign another contract with them. any suggestions for a good replacement? need to be able to duplex at least 300 gsm, good front to back registration, and good service, quickly, in dfw area.