RE: for the ROGER
If you changed the surface finish of your new F-161 you may not have hurt it's potential speed, early planing, or anything else, but on the other hand I think the craftsmen at Cobra take quite a bit of extra care to sand the F-161 to the finish that was on it when you received it.
Does the surface still "wet out".
It would be hard to make the surface "too smooth", but it is possible.
The only way to know for sure will be to go out on the water an see how your board preforms against other F-161's.
Hope this helps,