Better answer, to longer question:
IMHO it’s more about overall position than a single component like stem.
Personally, I think bar width made more difference to me.
eg
Two pics taken on the same day, coincidentally taken at EXACTLY the same point on the trail but on two different bikes.
When I saw these, I bought a bit shorter stem/much wider bars. Loads better now. 😀 😀
Only problem then was that my other bike, the Rockhopper, now felt crap down hills so I ended up putting the 60mm stem on that. 🙂
1. Meta 5 at 60mm with maybe 670mm-ish bars
2. Borrowed mmmbop at 50mm with 745mm bars