...I'm with the prevailing opinion on this issue.

There are really two types of efficiency. Runtime efficiency, and development-time efficiency. And you don't have to guess to know which one is worth more in all but a very few cases.

So except for high-repetition operations, and high volume operations, I opt for the data structures that support maximum exposure of the program logic. I usually find that a hash does this for me. (IMHO)

---v