Lo pro / Picco top handles, pole saws get 050. The rest get 063 whether is Husky, Stihl, .325/ 3/8/ .404 or even 1/2". You can swap bar noses and turn 3/8 bars into .404 etc. Good oiling, less drive tang maintenance/damage and virtually eliminates hard chips getting jammed in bar rails or seizing up nose sprockets. I have a few 050 3/8 bars I bought out of the US and soon realised why all Aussie delivered saws are sold with 063. Every day I'd be scraping out jammed wood from within the rails. With 063 compressed air will remove everything. But 'your' conditions dictate what works best and if I was cutting soft species 050 would likely be OK. Many use it successfully without any issues what so ever. It just depends. The only bars sold here by dealers in 050 are for Picco, you could go to every Stihl dealer (430+) across the country and find not one full size 3/8 050 bar. Only place you can source them is online from independent traders even then they are few to find. So gauge does have its performance difference, question is does it matter to 'you' or not.