I have posted the link to the proposed new rules - you should go and read them rather than speculate on whether they will apply (they will from 2012).
With regard to CAT:
Clearly the imposition of the cloud base limitation of 1,500ft at night affects a number of existing operations. The reason I mentioned that Eurocontrol did not consult operational experts is because it should have been clear that appropriate rules and mitigation exist in JAR-OPS 3 (3.465 and, for HEMS, the appropriate Appendix). This also applies to the 500ft rule.
Hence, both rules could have had an appropriate derogation to "or as prescribed in the applicable air operations legislation" put into Paragraphs 4.3 d) and 4.6.
With regard to GA:
Defence of the UK rules might be appropriate but they are rather out-on-a-limb in Europe - can the UK hold its position in a debate where they are in a minority of one. (Interestingly, the UK 500ft rule is similar to that provided for the US, Canada - not sure about other States.)
Helimutt,
Don't confuse the issue - it is the requirement to fly to the levels explicitly stated in the Appendix to the Proposal that is the issue; not that IFR cannot be flown. That might preclude all 'special' level structures that have been provided for opposing traffic in specific areas.
Rotordude,
Yes, it will have an effect both on night en-route let-down and night (and day) inter-rig shuttling - all of which have appropriate safeguards built in to 3.365 and 3.465. Not too much effect on the offshore en-route let down except that it will raise the forecast night cloud ceiling from 1,200ft to 1,500ft (based upon the fact that en-route let down will have to be followed by a VFR section).
Jim