The RR Sport is a smaller LR3. 3" less back seat room. The supercharged version is ok, but the equivalent BMW is faster - which sort of defeats the purpose.
The RR is really pretty nice inside, but everything I've heard (and seen at the dealership) makes me think that the electrics are even more delicate.
Personally, I'd stick with the LR3 unless you have a burning desire throw a ton of money away in exchange for nicer wood trim. If that's the case, then pm me - I have a maple tree out back that I need to get rid of. There's enough wood in there to trim a few dozen RRs...