Stumbled across [link=http://www.bobjellison.com/f9f_6_3.htm]this link[/link], which contained the following paragraph regarding the development of the Cougar variant of the Panther, confirming that it's a yaw issue and not a roll issue. IMO those seeking to fix the problem with roll gyros are addressing the symptom rather than the disease.......
To make the XF9F-6 Cougar design easier to produce, the Panther's fuselage, engine installation, wing center section, fin, rudder and landing gear were retained. The forward fuselage was lengthened by two feet to accommodate more fuel. The upper rudder was converted into a yaw damper; this was required to cope with the increase in yawing and rolling inherent to sweptwing aerodynamics in rough air. The wings were swept to 35 degrees, and hydraulic-powered leading-edge slats similar to the Bell L-39's fixed slats were installed. The stabilizer was swept 35 degrees and was made fully trimmable for high-Mach-number flight. Normal aerodynamically powered elevators were installed.