I agree, wouldn't even consider China Ebay parts for any of this.
You're a busy man, you've had to carefully plan and put off other things to clear this firewood cutting time. You've gotten up at 5am on a weekend, it's first light after an hour drive to the woods. You've just finished your bacon and eggs and taters, and poured a second cup of coffee(when I go to the woods, I bring a camp stove and do it right).
Time to fire up the saw and get to work. 18 pulls later you got two coughs and a wheeze. 20 pulls later you got it to run for three seconds. A dozen pulls and some carb screw fiddling later, you get it to kinda sorta run for a bit and then stall. You're dead in the water.
You did EXACTLY the same amount of work to install the Chinese parts as it would have taken to install OEM parts. You saved $50 on the Chinese parts vs. Stihl OEM parts. Now, in that instant in the woods with a boat anchor saw, would you hand someone $50 if they could snap their fingers and have your saw run beautifully? You're getting exactly that option, the only difference is the time period. You have to make that choice now, not in the woods.