Larger saddles can spread the load over a larger area and reduces stress fractures.
Plus the larger saddle is much more stable when jacking the vehicle up. If you do not have the saddle 100% centered and you have the smaller saddle the car could slip off the jack, not something you want to have happen. The larger saddle will cradle the pumpkin very nicely and you can actually move the car sideways using the jack under the pumpkin.
Randy Goodling
CCOA #95