Hmmm I'm far from wholly convinced though I may have a helpful discovery.
I fly in a Cub regularly and can check but it feels like the sims operating at 1/2 rate - everything feels like flying in treacle.
However I looked at the rudder which though assigned and independent of ailerons seemed to barely move. That would explain not getting the turn rate that the Cub can achieve and the ground turning circle taking in half of Europe. In reality I know the Cub can turn on a sixpence (with differential braking) - because I usually have a hard time stopping it!
All my controls were at full sensitivity and so forth so not that. It felt almost like fighting an autopilots control....Hang on!
The Cub may not actually have an autopilot, but do you fly other craft? If this is your experience also - go into a standard FS mooney - toggle the autopilot on and off then select the Cub again. Eureka! The rudder now moves as expected and both ground handling and turns feel more natural. I use Saitek panels a lot including the A/P so this may have a bearing (though they were unconnected in tests and the Mooney 'launched' with the autopilot off)
I'll check the roll rate further against reality, I may well be surprised. Things are after all so different when truly wobbling over England in a 60 year old canvas bag.
Otherwise I can only commend the beauty of the modelling, the totally authentic stubborness to start at times then immediately at others ( as though she never has a problem). There is a fault with the sound set though ... When she is being difficult I can hear the authentic compression noise etc., but where is all the swearing and cursing? It has to be the aircraft that makes these noises because it cannot possibly be us!