Steffen wrote on Jun 8^th, 2016 at 2:26pm:

If you use the ACE, and then SAVE any changes, that will change the aircraft.cfg, therefore changing the creation date. Make no changes, and the date won't change.

If you look at the aircraft.cfg file you might find why you don't see any difference between the variants.   They all have the same settings no matter E, H, J (KC,HC,LC,AC)

[TurbineEngineData]
fuel_flow_gain=0.02
inlet_area=1.0
rated_N2_rpm=29920
static_thrust=158
afterburner_available=0
reverser_available=1

[turboprop_engine]
power_scalar=1.0
maximum_torque=19600     ;H:maximum_torque(23030)

Not really sure how they came about these configurations for the maximum torque but all the C-130 legacy (E,H) models should have the Allison T56-A-15 engines, and the J has the Rolls Royce AE2100-D3

When you compare the older T56 models with shaft horse power you can see the difference.
T56-A-7: 4,200 shp (3,133 kW)
T56-A-14: 4,600 shp (3,433 kW)
T56-A-15: 4,591 shp (3,425 kW)
T56-A-425: 4,600 shp (3,433 kW)
T56-A-427: 5,250 shp (3,920 kW)
T56-A-427A: 5,100 shp (3,806 kW)

The 2100D3:
Power:
AE 2100 A/P: 4,152 shp (3,096 kW)
AE 2100D2 and AE 2100D3: 4,637 shp (3,458 kW)
AE 2100J: 4,591 shp (3,423 kW)

In regards to what you are seeing on climb out the difference in settings may be a place you look at (19600 vs 23030) on the maximum torque.