Correct
Checkairman,
Your observation is correct - take two 767's, one with GE CF6 engines, one with P&W 4060's. Both engines very similar in max thrust etcetera, otherwise they could not be an engine of choice on that one type of aircraft.
When spooling up the engines at the start of the take-off run, the P&W's spool up MUCH quicker off the idle RPM than the GE's.
Also, in flight, at the end of an idle descent, you have to anticipate that the GE's come off the idle RPM much slower than the P&W's.
Once a medium RPM has been established, acceleration is comparable.
This all is not a result of pilot technique - with both engines you start the take-off roll by setting the initial (off idle) thrust manually, then you engage autothrust, which runs thrust up to take-off setting. The initial manual setting CAN be done as a slam, to 1.1 EPR on P&W or to 70% N1 on GE. The actual acceleration will be regulated by the EEC's.
From what I gather from engineers, the GE's are a bit more sensitive to stall, perhaps their stall margin is engineered a bit tighter, resulting in slightly more max thrust than the P&W's and somewhat better fuel efficiency. Downside apparently, very sluggish initial acceleration.