DCO will generally be within 5% (max over operating range is 6%, but it is usually better) when properly calibrated. If the factory data has not been overwritten, then you can set the DCO to one of four calibrated frequencies, including 1MHz and 16MHz to keep within 5 or 6%.
You can check the calibration against the 32kHz xtal and trim the numbers to get closer, either by modifying the DCO constants or the settings for the UART clock.
If the 32KHz xtal is already there, then by using more advanced features of the UART clock, you can do a lot better using the baud rate modulator than with only the divider. See slau144, section 15 (in slau144i, it is page 430, and subsection 15.3.9) where one of the examples is specifically 9600baud using the 32kHz xtal.