I've had an F-type for a year and now an F160.
The F160 comes with a Drake R13 70 cm and works realy great!
But after I damaged that fin I borrowed an R19 70 cm, the one that comes with the F161.
Correct me if I'm wrong, but the R19 seems to have more rake and feels a bit stiffer.
With a wider F161 (more leverage) that stifness might be good, but under an F160 I prefer the R13.
An F-type is a bit more narrow 1 feet off compared with an F160, so I think that the stifness of an R19 would be more of a problem then.
No science, I'm just reasoning. So correct me if I'm wrong!