So is that model worth it for the points? It is an awesome mount that is not a large target, with a guy that can kick ass on top. Check out the setup that looks sexy with him:
Saurus Oldblood (1#, 465 Pts)
1 Saurus Oldblood @ 465 Pts
Hand Weapon; Light Armour; Scaly Skin
1 Carnosaur @ [210] Pts
Causes Terror; Large Target; Scaly Skin
1 Scimitar of the Sun Resplendent @ [50] Pts
1 The Maiming Shield @ [30] Pts
1 Carnosaur Pendant @ [20] Pts
This guy gets 8 str 5 attacks, 9 when he causes a wound. The carnosaur does 4 str 7 attacks, 5 when he causes a wound and D3 for each wound on large targets!

it is crazy!
Or in the long run is a Slann-mage priest a ton better?
Or does it depend on playstyle?