Hmmm... thank you all for your opinions and replies.
Firstly (and foremost), my apologies to the boys and girls at LATCC - I did not mean to imply you guys weren't **** hot at what you do - I'm well aware that you nail the 2.5NM final approach spacing day-in day-out... what we're not trying to do is upset that natural skill. Saying that, I didn't realise you'd discontinued use of the FAST tool - shows what happens when controllers aren't consulted right at the beginning of a project's development (i.e. they won't use it if it doesn't help).
There seems to be (from initial views) a dichotomy between the States and UK(/Europe?)... I was aware this existed, but not how pronounced it was. I think a lot of the ICAO PANS-RACs are developed with the US in mind, hence the problems with them in ECAC airspace. (and the difference in the perceived definitions of visual approach/separation, as mentioned by the 'Duke' above).
A question regarding Scott's post - how do you resolve the IFR / transfer of separation responsibility problems, as mentioned by ATCO2.... in theory, you can't have an aircraft operating IFR, yet maintaining own separation.
I'm NOT advocating visual approaches... I think they've been brought in without any regard for several important issues (responsibility, safety criticality etc).
My original question has pretty much been answered as far as the UK is concerned - any controllers from the rest of Europe care to comment?