No Mach Tuck. Speed sensing provided "speed stability" as the boffins called it and the tailplane was positioned and was powerful enough to overcome any of those aerodynamics effects. so you hade normal control over teh whoel speed range.
Straight wing aircraft without the speed stability function had Mach Tuck and if I can remember correctly one only got Mach Tuck on subsonic aircraft when the download on the tailplane...and other "stuff" changed.