I'd wonder about a conflict of interest...if company selling machine buys lots of Haas machines and uses the HFO services are they going to offer a blunt no nonsense answer to the buyer they do not know from Adam. Kinda don't sh$t where you eat.
I could be 100% off base...but something I have wondered about when I tried to have HFO go take a look at a machine for me.
It may be better to use a well respected private service tech...preferably one not used by the company selling.
Now what I found to be very helpful from the local HFO is they can provide you with service history of machine. Some machines, like mine are serviced by the HFO and they keep a record of work done, parts etc. Expect to see a few limit, proximity switches, servo motors, amps...older machines vector drive power supply etc. Normal age related stuff would not scare me. When I see several visits for ball screws and nuts, sheet metal replacement and axis realignment I think maybe its time to keep looking.