[Glider]

Tomcat
Find any pilot of any nation including German ones, who found the Spitfire difficult or unpleasent to fly. If it was as difficult as people are making out you should be able to find someone.

Just remember that Molders described the SPitfire as being faultless in a turn and childishly easy to take off and land. He found it much easier that the Me109.

Stability depends on what you want out of the aircraft. As I tried to show with the different Gliders, the dedicated aerobatic Fox was far more sensitive than the others. A Fighter needs to be more sensative than any other type of fighting machine because of what it does.
This goes back to the first air combats in WW1. Generally speaking the first RFC fighting aircraft were too stable and couldn't mix it with the German fighters. This trend was broken with later fighters until the Camel which was probably too far the other way. Even here the establishment SE5a was more stable than the Camel. Stability is't one measurement, there are degrees of stability. Many bi-plans were marginally stable as you say, but many were very stable it depended what you wanted out of the design.

I admit that I don't understand your statement they would hve taken great care that the ailerons had the same sensitivity The ailerons are the same in each wing, but its late and I might be missing something obvious.