There is quite a bit of apples-to-oranges comparisons going on here.
If you want to properly compare razors on terms of sizes only, make sure you:
* compare the same grinds
* compare the same grinds
* compare the same grinds
* compare edges of the same keenness, i.e. fresh sharpened by the same honemeister
Honestly, I cannot tell a general difference in smoothness between Sheffield and Solingen steels. Some of my Germen feel smoother than some of my English and the vice versa. What matters more than steel is often the blade geometry, especially the edge angle AFAICT.
Small blades require you to have a steady and sure hand. Unlike the heavy blades, you are in full control of what is going on. Heavies can be often just dragged along and their weight and momentum smoothen all the irregularities in your motions.
My 2c.