<<There is no evidence that where obs are done by non-Met Office staff that the quality of reports is significantly different to those done by Met Office staff. In poor wx RVR is done the same way as it always has been and is provided direct to the controller rather than coming via the met observer.>>
It's the cloud bit for LVPs which I understand may cause problems... Met Observing is much like ATC - it needs constant practice to become really efficient. I was one of the first UK ATCOs to be trained as a Met Observer and despite many weeks of working alongside the experts I had great difficulty with some aspects of the task.
I personally think it's ludicrous that major UK airports do not retain a full Met Office such as existed when I started at Heathrow. All down to the bean-counters..