I don't believe there is any difference in accuracy between wind-up and wind-down.
The difference is that wind-down can be used for a number of different problems, not all of which can be solved with wind-up, for example (I think, if memory serves me correctly) calculating wind speed and direction given heading, TAS, groundspeed and track. Because of this, it is the preferred method for wannabe CPL students who will have to solve problems like this for the ATPL written exams. But for a PPL who is not intending to take commercial exams, the wind-up method is slightly easier to use.
FFF
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