Of course they said it was accurate, did you think a sales person would say anything different? I doubt they have done an accurate calibration test, they might have but I doubt it...
I wouldn't do it but without seeing them it's hard to give an accurate opinion...
I've bought a Punch Rothchild there recently and it was fine, but I don't recall seeing a hygro then.
__________________ "Man's mind is his basic tool of survival. Life is given to him, survival is not." -John Galt