I tend to prefer the original carb because it has a fuel pump pulse system designed by Stihl to work best with the unique Four Mix design. Other people however, have used other carbs with success. Your choice, but if you have other carbs available, it is no big deal to swap out that little high speed check valve to one robbed out of a two stroke carb. Rebuild your carb with new diaphragms for best results while you have it apart.
Your original carb does have a high and low mixture adjustment, right? All the 4m's I played with did. If not, then yes, I would say to use a different carb. High and low mixture adjustment provision is a must have deal.
AV8TOR