Hi there,
I will try and answer your question as best I can.
Out of London on our usual Midhurst departure, there is a note on the Jepp plate concerning a gradient until 4000 ft. Instead of accelerating earlier, our company prefers to to continue the climb at V2+10, as per the performance until 4000ft before automatically going into CLIMB mode and accelerating. Begining the acceleration phase at an earlier altitude brings you closer to the noise monitoring equipment, thus an earlier triggering of the "bells" exists.
On all occasions, on departure, we realise that we are slow in the climb or to acclerate, but we feel we are not breaking any laid out/chartered rules. Should you require earlier acceleration, you may inform the crew out of, say 3000ft "continue acceleration" or "no speed restriction". Secondly, we never want to block the frequecy asking about acceleration at an earlier level. Usually the greendot speed (best lift/drag) at 270 tons is about 272 kts indicated and this is where the A340 would be best to climb at below 10000ft. After 10000, the climb speed/mach differs from company to company, due to the different Cost Index selection. CI-50 is different to CI-80 or CI-100 of another company. VA, Sri Lankan and other operators use different Cost Indexes which differ the performance of the A340, from each other. Technique is also different in various companies. Even the old VOR approach is done different in A340's between companies too. Some do fully mananged, other do fully selected whilst we are familar with managed lateral, but selected vertical. That's 3 different ways for 3 different airlines in just a VOR approach.
Further more, the A340 climbs very well with an engine out as it is only on 75% thrust when compared to say an A330 at 50% thrust with one out. I would prefer the 3 engine climb.
I hope this helps and I am open to learn more from the next guy, in the posts.