Recover:
I am not certain about this but I was under the impression that the 500' ceased once one was out of the hold and onto the intermediate approach. If anybody knows better I would like to know myself.
In my experience, British Midland stand head and shoulders above most when it comes to following CDAs. They are so consistently good at it that I have often wondered if their company ops. people bash it into them during their 6 month recurrent. Is that so?
However, CDAs are great until you have to cross over the 'other' approach when landing on both runways. Getting over the top of a slow descender (especially if its a heavy and vortex is involved) tends to force a late and rushed descent for the succeeding. It becomes time critical, demanding r/t priority and it is easy to forget to 'turn in' the next one. To make it easier for me, I usually explain my problem and ask for a good rate to 4000' (or better still, 3000' if I can get it off Thames) thereby throwing away the CDA!
So as HD says, CDAs and 45 an hour don't go together easily.
Point 4
