Generally speaking if you could beat those players, it's always better to buy in for the full amount. Otherwise you will loose value on your big hands.

Just be aware of your position relative to real small stacks at your table. Maybe they will try to raise you allin preflop and steal your raises. If you see the smallstacks moving allin preflop repeatetdy with medicore hands against your raises you can go for it with a good hand - just be sure to push allin to isolate your oponent.

As always in poker you have to look at the table condition to make this work. For example, don't do this if the shortstack push has already been called by another player, or if there already two or three oponents in the hand which have called your raise.