I suppose my view is that (I thought) you really couldn't go wrong by reading back the controllers clearance verbatim, e.g. they say "climb to 2000", I say "climb to 2000", if they say "climb altitude 2000", I say "climb altitude 2000".
There are enough variations on the planet that this seems to be the only way survive if you operate on 6 continents. On the other hand I could just adopt the policies of my native country's agency and say "climb/descend and maintain" or "turn left/right heading". In the end I guess you can't please everyone, but when you fly with someone who nitpicks you in can get a bit maddening
Thanks for the responses!