Hi, you will find that the DME requirements for curved approaches include DME/P (precision) as opposed to the normal DME with which the civilian world is familiar.
I can also comment on when MLS would provide a benefit in Low Visibility Procedures.
You do not need a string of BA A320 family to be available, you can put a MLS equipped aircraft at approximately wake vortex + 1 nm behind anything, where wake vortex is the normal in trail separation criterion, or about 4 nm if it is not. For the mixed mode operation, then you can ignore the localiser overflight requirement as the transient is not the same. In addition, some well documented work I did in the past showed that the current landing clearance delivery points (Outer Marker, 4 nm, or 2nm exceptionally 1... and we all known that Gatwick is an exceptional place...) could be reduced down to 200 feet above TDZ elevation without a problem, but might need a bit of tinkering with the flightdeck callouts (if you are a one hundred above and CAT II).
At LHR, the most logical solution for the current mix would be BA A320 family to the departure runway and continue the ILS stream to the other. This used to be (and I am not sure about current procedures) acceptable against the runway alternation procedure because it was suspended in LVPs.
MLS LVPs have no ILS sensitive area restrictions and the critical areas are not affected by flightpaths of aircraft (but still exist for ground vehicles parking in front of transmitters etc).
As for curved MLS approaches, not sure if the Space Shuttle counts still or approaches to distinctly mobile aerodromes which float and may not operate with all of the relevant Annex 14 separations provided from other aircraft when parked. The runway lengths are also well inside the Code 1 length.... I am sure you get my drift, which is what they do with currents, tides and wind!