We fly A332/A333/A345/A346 as MFF and there are a lot of weight differences and ranges, including speed and the cockpits look very much the same, including 500 and the 600. That being said, I know of a few cases where the correct weights have been calculated, but incorrect fuel has been uplifted which is also a problem. Example, pilots uplifted 43.8 tons instead of 48.3 tons, a difference of almost 5 tons (an hours flying in A330) short. Speeds were good, but fuel was wrong!
In another case pilots have uplifted trip fuel instead of flight plan fuel on the A320, only to have an embarrassing chat to ops about where to land enroute for a technical stop.
The list goes on and on and all the mistakes have slipped through the system design to catch it, but it didn't. Human Factor is a natural problem, which makes us infallible. We need to slow down and have time catchup with us!
Most companies require pilot to individually calculate the take-off figure and then compare the figures, including the green dot speed. But when chased for time, we work over the other guys shoulder, cross communicating the weights being used or weather and hence we are doubling up on the wrong information and will have a problem.