Bear in mind three things:
1) The AIP demands at least 500 fpm.
2) If you report leaving a level we are legally allowed to clear another aircraft to that level. So don't say 'leaving' unless you actually are (i.e. not before you've pushed the level change button or whatever).
3) Technically we are not allowed to use Mode C info in the hold (although many do), so if you call out of a level and the next one is in a continuous descent we may not spot the closure if you are too slow descending.
------------------
"Take-off is optional, Landing is mandatory"