Ye, of course it depends where you reside. But here, there's no problem at all when repotting first half of August. Then roots are still developing fast, and... the tree does not shut down and stops growing
Milage varies. It gets very dangerous generalizing something based on your experience in your location. Things you can do safely in your location at a certain time can kill a tree if it's done in another location.
August where I live is very hot 90-95+ degrees Fahrenheit, and can have little to no rain. I believe you have more rain and it's cooler typically where you are in August? Your winter is also typically milder? England where Mr. Harrington is located is usually cooler in summer and has a milder winter than here.
I've repotted scots and mugos in early August here with success. The mugos seem to fare better than scots, but I've had mugos stall and sulk after a summer repot then be very slow to get going the following spring. I've had half of my scots die after repotting in August.
None of my scots or mugos have died with a spring repot and in all cases recovered faster than any of my summer repots while the mugo done the summer before sulked. I believe the differences is because of my climate and seasonal patterns.
I just think it is smart for people to think about their situation before blindly following what someone else halfway around the world in a very different climate is doing.
