[a_t48]

When there will be multiple shorter passwords that hash to the same value, is there a point to a 20mb pass?

[ColinWright]

Yes. Ideally you want users to be able to remember their pass-phrases. To do so usually implies significant internal structure and/or correlations, so to get the necessary entropy they will be large. The fact that they hash to the same value as other things is effectively irrelevant.

[gherkin0]

I misspoke, I meant size.

[elektromekatron]

Depends. Can you guess them?

[a_t48]

If I'm an attacker who is running through hashes...yes. Faster than the 20mb one.