The secret to flying a 109 is multi-layered.
A. Throttle control
B. Rudder control
C. Easy on the stick
D. WEP
E. Climb Rate
F. Gunnery - you're on your own for this, I suck at aiming and wept when they stole the gondies from the 109f's.
The 109 is so responsive to throttle inputs that it's definitely a factor in maneuvering. For most variants, wep gives a significant speed boost for as long as it lasts - which gives them that boosted climbrate.
The real secret, tho, imho, is using the rudder and throttle and when going for those hammerhead moves (or any over the top wingover) is letting the 109 get you there - forcing it is where you lose it.
The biggest threat to 109's are yaks and lala's when down low because they also possess great power/weight ratios and can hang with the 109's nose up until you get over 12-15k.
The 109's biggest tactical advantage is the ability to bleed the opponents e and from there stay nose up. Hogs, ponies, spits can only hang with a 109 for a limited amount of time and are most dangerous when you're doing downward scissors. If the 109 can take/keep the battle nose up, it will generally win.
The 109's are wonderful little rides - I've spent quite a bit of time in them in the old AVA/CT arena.