Depends how you drive mate,
2.3 as far as I can remember revs @ 2700 approx at 70mph
3.0 just over 2000 at 70mph
I get anywhere from 36-41 avg 65-70 on a long motorway run loaded,
You can travel at 50mph ticking over @1500rpm 50+mpg if flat roads
If you do mileage (I do 100k a yr) then add in the saving from not changing a belt every 110k, in my mind
3.0 is by far a better driving lump,
But,
If you like to have fun, drive a lot in towns/cities, stop start, twisty hills
Then the 2.3 maybe better as the 3.0 does drink over 65mph and cities etc
Hope that helps
Plus, just gone over 330,000 this morning still on original clutch, only 2 throttle valves, 1 turbo under warranty from water ingress. But we do have a hesitation that's not showing up any faults, possible throttle pedal that needs investigation