Hey Jas.
I have a 98 GU 2.8 TI Done around 200k.
Every day driving I usually change around 2800-3000.
If I am overtaking and need to get the baby going I can push it to 3800-4000 and it loves it.
Mate in a 200 series cruiser (V8 twin turbo diesel) is actually shocked how well the trol sticks with him on the open roads.
They love to tow loads, but as Tony said, they will slow a bit on hills as most vehicles do with a load.
Without a load as long as no-one slows you down and you get a run at the hills, they handle it pretty well.
Yes the bigger engines are better offroad as you would expect but I have NO problems at all off road with the RD28Ti. (mud,sand,rocks,water, all good) as long as you keep them reving.
Its a beast, I love it and have no prob' recomending it.

All the best with your decission Jas.

Cheers Pete