I think that by the time you get to 500'agl you know whether the PFL would 'work' or not. Remember also the wording of the rule - you can go lower than 500' as long as you are more than 500' from man made objects, vessels etc. i.e. pick a big field then you can go as low as you want. You can also practice the entire PFL at an airfield (provided it is not too busy). I find that carrying out a PFL from start to finish at a grass airfield is an extremely valuable exercise and is probably more difficult than landing in a field (which would hopefully be bigger and wider). I can't imagine the CAA changing this rule. I'm not sure I agree with the previous post - I don't think reducing/changing the 500' rule would cause more accidents - but it would be likely to cause more complaints, particularly from livestock owners/horse riders (and I suppose the possibility of accidents on the ground with the latter).
The EFATO question is much more difficult. I think if you practice EFATOs at an airfield with a reasonably long runway and the student demonstrates that he/she points the nose down and aims somewhere sensible I think that's about all that can be taught. I'm not sure how much skill is actually required in an EFATO. Provided you don't stall the aircraft, surely the outcome depends on the ground around you, which is either favourable or not. I wouldn't fancy having an EFATO at Southampton...
I think spin training probably has a place in training (although probably not for PPL), but I would never ever do it without a parachute.
And on the IMC question - if we had a sensible instrument rating in this country with the emphasis on currency (i.e. FAA IR requires 6 approaches in 6 months) pilots would be much more skilled at IMC flying and people would stop using the IMC rating as a 'get me home' rating (which is not a particularly sensible idea, IF should be practiced often). But I'll stop now - I could go on all night...
Samson.