What are the functional differences between the Mauser 1909 straight feed rails vs the stepped K98 type feed rails?

What are the preferences of the guys that have worked on and used both a lot?

For Std Mauser head size?
For larger head sizes?

I have found they will feed practically any round that will fit through the feed ramp opening. The pinched type used in other M98's can be a little more finicky, especially when going to fatter, shorter rounds like the .308 family.