On Fantome's chum's points:-
I'm certainly not a Yank, and most of my flying is from grass runways under 800m thanks very much!
780lb was the useable payload on our 108-2 - 1450lbf empty weight, 2230lb MTOW. I weighed it myself with calibrated 3 point aircraft scales. We still had a non-functioning auxilliary tank in the back and probably a bit more paint than it needed, but that was certainly not 320lbf worth. Anyhow, the OP turns out not to have a 108 anyhow.
Runway length experience was based upon practical use of (mostly) grass strips around the UK and Ireland - so roundabout ISA S/L, and was basically my comfort zone and not trying to prove anything. I'm sure that somebody with no sense of fear and a determination to prove a point could fly the type from far less. And yes, I did use flaps as god and the POH intended.
Every pilot I checked out on it, had a tendency to inadvertently pull back on the yoke and bleed speed off when correctly trimmed, until this was beaten soundly out of them. I suspect I did the same my first 15ish hours on type as well. It's correctable and seems to be a function of climb attitude, seat angle, and yoke ergonomics.
The apparence of some mainwheel braking at full rudder deflection was normal, and I thought I'd seen that in the maintenance manual somewhere, although could be wrong as I can't see it in the POH I have to hand.
I think that in retrospect Fantome's chum is absolutely right about needing people with Franklin experience to look after a Franklin. Unfortunately, there is nobody in Britain with significant Franklin experience.
G