In order to go to college - a whole lot of years ago - I worked a lot of jobs during a lot of summers. One of those jobs was as a truck driver. I was not licensed for 18 wheelers, but any box truck, no matter how big, was mine...
Because I was the youngest guy on the crew, I got the oldest machinery. Most was early 50s vintage. These trucks all contained manual transmissions, with no synchronizers. Learning to double clutch was absolutely necessary. The sound of crashing and gnashing gears was not only unpleasant, but if created within ear shot of the main garage, it was fodder for much derision by the older drivers. The boss certainly did not like it, either.
There have been threads on the MT Legacy's reluctance to shift easily, first thing on a cold morning. I agree, completely. The suggested fixes have mostly been in the area of a fluid change in the transmission - said change ranging from a Subaru product, through 3rd party products, to cocktails. All entail expense and trouble.
Probably out of habit, I have always double clutched my 6MT during down shifts from 3rd gear to 2nd gear, while going around relatively slow corners. Well executed double clutch shifts are very satisfying... I have noted that there is always a finality - a solidity - to the shift, that synchronizers simply do not create.
So, weeks ago, after backing out onto the street from our garage - at around 15 degrees F, I decided to double clutch the shift from 1st gear to 2nd gear - the shift most often mentioned in the threads concerning the cold weather challenges. The procedure produced a perfect shift - no drama, no issues. Hmmm. Transmissions warm up quickly, so I could not try it again that morning.
Many weeks have gone by, with many 1st to 2nd gear upshifts in very cold weather. The result has always been the same: The shift is performed with no cold weather drama.
Simply a heads up... You might wish to try the process with your own 6MT. Nothing is perfect, but this certainly works for me...