Re: 1796 Giovanni Battista Fabricatore mandolin
To answer my own query...
I would say that best case the strength of the bar is only as good as the strength of the glue joint between the bar and the top. If you repair the bar, your glue joint will presumably be no different (stronger or weaker).
With that observation, I guess I'd do what I could to repair and keep the bars.
"The effect is pretty at first... It is disquieting to find that there are nineteen people in England who can play the mandolin; and I sincerely hope the number may not increase."
- George Bernard Shaw, Times of London, December 12, 1893