The Xante is a modified Okidata. I have a PSI system (Okidata 3650), an Okidata 9850, and three 9600's - 100M a month is no problem. Best to view these engines as disposable - so relatively inexpensive that you can afford to run them until they die. Beauty of the Okidata is that 95% of all wearable parts and components are user replaceable.
If you recharge the toner cartridges yourself, there is no lower-cost, high-quality engine on the market. The straight paper path is the reason you see Okidata printers used exclusively in laser envelope configurations.
Oki just came out with a replacement line, 910 & 930, but stay away. The 9650 is cheaper and the toner and toner chips necessary for user refilling won't be available for a couple years, if ever.