Tell us how you get on, they may also be able to explain the whys and wherefores of RRS wading depths. 

"Roads ? Where we're going there are no roads." Back to the future.

Discussed the wading depth issue with one of the LRE guys at Eastnor. He also drives a 57 plate TDV8 and is of the opinion that the depth is 700mm. I mentioned the owner's manual saying 560mm. He was quite confused by that and thinks that it might have been an oversight/error in the manual. He was convinced that the RRS and D3 both had the same wading depth from the very start.

Unless someone has contact info for LR technical department at the factory, I'm not sure this will be answered any further.

As an aside, he did say that, having spent a week with the new FFRR he thinks it a very capable machine. Apparently when they were testing it at Eastnor they couldn't get it stuck and had to make some new obstacles to test it out properly including new wading trenches. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

The new FFRR has a wading depth of 900mm '08 RRS TDV8
I converted my diesel RRS to run on an environmentally friendly mixture of caribou fat and baby seals oil