P will help Band-Aid it a touch in the first part of the travel, but the effective rate will indeed end up stiffer in P than F in the latter part of the travel. That's what P is for after all, to support a passenger's weight without making the bike unrideable solo.
Every company that makes performance-oriented aftermarket suspension links for streetbikes makes them linear/flat, or at least less progressive than OEM links. There's a reason for that; think about it.
Will the ride feel firmer for a given spring with a flat link vs a progressive one? Yes. But it will do a better job of controlling the chassis than a progressive one under aggressive riding. At your weight the bike is simply oversprung for road riding. No matter how quick you go on the road, the loads put into the tires and suspension are nothing compared to on the track, so you need softer suspension for it to work properly. Not to mention how much rougher the surfaces are; even a relatively smooth road is not as smooth as most tracks.
Bottom line, springs are cheap, and you need them. I'm 155 out of gear and am running 80N on back and 9.5N on front on my base model with the link on F. Preload/Sag settings are where you'd want to see them now, whereas with the stock springs the preload was way too little to get sag in the ballpark. Needs a bit more oil height to limit brake dive in the front, but otherwise it works much better than stock now on the roads I ride.
