I just purchaced a new MDS .58 last week and the needle valve has a noticably longer taper than the one on my first .58.
I always said that the short taper was what made the MDS engines so hard to tune, a few clicks either way and you where out of the ball park! I hope this helps the image of these engines. I have always had acceptable service and performance from the MDS engines I have owned or still own.