I haven't bought a reproduction, but after having seen the original, I am torn. I cannot express to you how moving the original was to me. Mrs. DoodleBob said I was (unintentionally) rude because I stood right in front of the painting and looked up real close, and blocked others' view. Then seeing that Mercer's St. Joseph was not sleeping made my heart leap with joy because it reinforced my own view, that St Joseph was not some silent old man but a bedrock of strength.
If you get a chance to see the original, please do it. In fact seeing the original of anything is always a worthwhile quest. And as SunkenCiv noted, the MFA is a great museum.
The only thing that could use improvement (and granted, I've not been there in years) is the Greek and Roman classical collection -- not least because one gets there through the Egyptian collection. If they ever build a new house, they should keep the Egyptian collection monolithic, but spread the Roman and Greek stuff throughout the rest of the museum.