I have a near complete set of MF bench planes that are all corrugated.  I
have a several flat soled Stanley Bailey planes.  Comparing a number 5
Stanley to a number 14 MF, in use, I cannot tell a difference, except, the
MF is slightly heavier.  However, I have not compared a smooth MF to a like
corrugated MF or vice versa for Stanley.  However, imho, there is not a
significant difference in use.  It does seem to me that it is a little (and
I emphasize little) easier to flatten the sole of a corrugated plane.   I
think it is similar to the idea of flattening the back of a Japanese style
chisel.  Less metal to remove.

Doc
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