Bessacarrs are based on Swifts current at the time range topper, with extras, so make a good second hand buy, all other things being equal. What may normally be an extra on other ranges is included. Note that as part of the Bessacarr package, the MTPLM is usually uprated, so don't expect any further weight upgrade to be possible.
At one point Swift planned to end the Bessacarr range as they admitted they could not meet the quality requirements of the loyal band of owners used to the original Bessies, so that tells you the quality was aligned with Swifts usual standard...