I had an old XL when they were blue. It shook so hard that the handle screws would come loose and jump out and I would catch it while I was cutting.
I think it was a 330 that I bought brand new. I used it about three months in Alaska before something came apart under the flywheel. I got it fixed but it wouldn't run at all at over 10K' ASL in Colorado. For that matter, neither would the Huskies of that era. They would run about ten minutes and then you would have to let them cool off a while. Stihl had the isolated carb so it wouldn't vapor lock.
Then I had two 045's that I ran for years. Always need a spare when you're 50-60 miles from town. I got talked into modernizing and bought an 044. It did okay until I blew it up on a hundred degree day in Montana. So then I bought the 046 and stihl running it today. But I only used it professionally about six months.
Stihl don't like cold weather though. You have to work them really hard to keep them up to operating temperature in the winter. Firewood cutting is okay but falling/limbing they start to sputter. If I was timber falling again, I would run Stihl in the summer and Husky in the winter. Trouble is they don't use the same bars so you have to duplicate everything
Doesn't matter since most all jobs is feller-buncher anymore. Sit in a cab and push buttons and look at a computer screen.