Component lifetimes ARE reduced as a function of operating temperature. You can find a slew of engineering whitepapers on this. Different components (electrolytic caps, microprocessors, simple passive components) are effected in different ways, but running without the fan may have reduced the expected lifetime of the system. Of course, if the effect was to reduce the lifetime of some component from 40 years down to 30, then it's pretty much a non-issue. (Sure, there are a number of 30-year old effects processors that still have value, like the TC2290, but generally speaking no one's lining up at the door to scoop up that pink and black A.R.T. effects processor you bought back in 1985.)
For only a $400 difference, I'd probably chose a new unit for the warranty and peace of mind, but the unit you bought from GC should be just fine. Of course, I've seen people dump gear at GC because it had some intermittent issues and they wanted to get rid of it without selling it directly to a real person. That's the "peace of mind" aspect that would lead me to likely opt for new unit.