I agree with A300PilotAmerican in relation to the thrust been Sluggish. I have tweaked this in X-plane maker. If you go to the menu and then hit standard, engine specs, then to the right, Start/spool up and change "compressor spool up time" to 7 sec Check fuel pump advance time is at 3 seconds too, I think it is by default anyway. Then you closely resemble what I hear in the video I've linked. I know the A310 in the video has the PW engines, but even they are slow to spool on the ini A300.
With regard to climb performance, I have no idea and trust that the sim is close to the real thing? ..