With regard to the 737 vs Airbus comments:
The 737 is not currently availabe with a Cat 3B option and I heard this was because no one had requested it as an option. Easyjet has now and there is a possibility that it may be available in the future.
RVR is measured electronically by a device that I cant even pretend to spell
Ok I'lll try - transmissometer
There are three of them next to the runway giving touchdown, midpoint and stop end RVR's. They are often not indicative of the visibility needed to land as the are not placed at the pilots eye postion but instead at a few feet above the ground. They are often affected by ground fog, such as on 23 at GLA where the waterway near the threshold can affect the transmissometer despite there being clear vis.
Its an odd system!
.con