If going too short, efficiency is reduced in all powerplants - springer, PCP, multi-pump pneumatic and CO2.
Specifically in a springer, restoring power (if required / desired) will generally need more spring / preload, leading to a harsher cycle (gun dependant of course).
Short barrels can be very accurate, as witnessed by the accuracy achieved by match pistols, HW44 etc.
I'd say the main advantage of a short barrel is the compactness for shooting in confined spaces / from vehicles as pointed out above.
Personally, on a break barrel springer I'd prefer 16" minimum and I certainly don't mind the longer barrels of rifles like the HW35E. In fact, especially if using open sights, the longer sight base has to be seen as a definite advantage.