[Dovecot] Postfix LDA vs the Dovecot LDA + other quetions

Guys ,

1. What is the benefit of using Dovecot' LDA as compared to postfix's LDA? Will there be better performance?

And along the same vein,

2. What is the benefit of using Dovecot's SASL as compared to Cyrus SASL? Is there better performance?

3. Quota Management ( Creating, enforcing, notifying ) - is it done thru dovecot or postfix or are both needed?

Regards, mgomez