Dragon Bomber maximum angular speed in radians/second: 1.0688
Barghest maximum angular speed in radians/second: 0.8667
GC Bomber maximum angular speed in radians/second: 1.0750
For comparison against fighters:
Titan maximum angular speed in radians/second: 1.1220
Sabre maximum angular speed in radians/second: 1.2250
Eagle maximum angular speed in radians/second: 1.3049
For comparison against other bombers:
Rheinland snubnose maximum angular speed in radians/second: 0.9111
Praetorian maximum angular speed in radians/second: 0.9556
Upholder maximum angular speed in radians/second: 1.0500
Note, these figures reflect a general radians/second maximum rate of turn, not rate of turn in a particular axes. For example, bounty hunter capital ships tend to turn faster on the horizontal axis to allow their wide flanks to be exposed.
As you can see, the GC bomber is quite nippy, compared to the Barghest. The armour and powerplant are sacrificed for the extra agility, which should be quite easy to feel. It also allows the GC bomber to better defend itself against fighters when compared to the Barghest.
EDIT: Figures from FLstat.
EDIT2: Radian = 57.2958 degrees