So, it seems that stock cooler isn't that good after all - it's too inconsitent.
Had same thing printed twice, and they should had the same cooling, but one came warped.. other didn't.
I gave your v10 another chance and unfortunately I had similar cooling issues.
Perhaps the fan is not powerful enough? It's pretty quiet for a radial fan, even on 100%.
If I may recommend something - why not try to make MK2-like shroud, that blows air from the front only?
Most printers have such shroud and they work well, maybe it's worth the shot.