Tigger,
I used to have a GQ 4.2 with a Safari Turbo, and absolutely loved it ......
I have since owned 2 Di's and 2 CRD's and do everything that I used to do with the 4.2 and more.
There is a learning period between the 4.2 and the 3 litre engines, as you need to drive the 3 litre to achieve the same results .... you cant just get out and walk beside the truck up a hill like you could with the 4.2 ..... keep the 3 litre around 2000 rpms at all times when climbing and it is all good.
Also get used to stalling a bit till you adjust to the new driving style.
Things you will love in the 3 litre .... slightly better economy, better road manners for driving in traffic ( better acceleration / more carlike ), the auto, the big one 10000 klm servicing
Things you will hate ..... the lack of off boost torque
After owning all three types, I prefer the CRD over all, even though they dont go as hard as the later Di's.