TBH it's been a while since I've done these contests seriously, but I remember the "order of computation" problem to be hard to think about for less trivial cases (like with a 3-dimensional table). But maybe I worried about it too much.
And just for fun, while we're listing these things:
Another advantage to bottom-up that I've seen is that sometimes top-down causes your recursion to get so deep that you run out of space in your call stack. Another advantage to top-down is that you're only filling in the subset of the table that's needed for the specific problem you're solving. Certainly someone with a lot of experience should be able to do both.
Some examples where order of computation isn't that trivial is when you're doing DP on trees or a DAG.
+1 to the "filling in a subset" part. Usually it's not too relevant because it's merely a constant factor change, but occasionally it'll be very important.
And just for fun, while we're listing these things:
Another advantage to bottom-up that I've seen is that sometimes top-down causes your recursion to get so deep that you run out of space in your call stack. Another advantage to top-down is that you're only filling in the subset of the table that's needed for the specific problem you're solving. Certainly someone with a lot of experience should be able to do both.