I also have a NH 273 baler that I've had for about 8 or 9 years. I put up 2000 bales per year. Like everyone else, I'd say it's a good baler.
However, like every other mechanical device, you can expect breakdowns. I've replaced one drive chain, multiple pick-up tines, one tire, a few shear bolts, a drive wheel for the metering arm, one set of knives that cut the twine, one bearing on the plunger mechanism, and other miscellaneous stuff.
I keep mine well greased and shedded. You MUST have an owner's manual so that you'll understand the many adjustments that can be made and find the many lubrication points.
Good luck on your decision.
Tom in TN