Identifying to your services account via SASL instead of NickServ IDENTIFY is advantageous for a number of reasons:

• You are identified far earlier in the connection process (before the rest of the network knows you have connected, even). This means that you can instantly join registered-user-only channels, match an invite exception based on your account name, join a restricted channel that you have access to without worrying about services kickbanning you, etc.
  
  
• Your client can be usually configured to abort the connection if SASL authentication fails for any reason. This is useful if, for example, you always want to join channels with a vHost instead of your partially cloaked hostname.
  
  

The AlphaChat IRC Network currently supports the following SASL authentication mechanisms:

• PLAIN
  
  This mechanism uses your account name and password.
  This mechanism is widely supported by IRC clients.
  This mechanism requires you to be connected via TLS to use it securely (your password is sent in plain text otherwise).
  This mechanism requires you to trust the server (to not log your password).
  
  
• EXTERNAL
  
  This mechanism is basically CertFP.
  This mechanism requires you to be connected via TLS with a client certificate.
  This mechanism requires you to trust the server (to not tell services that someone else is connected with your fingerprint).
  
  
• ECDSA-NIST256P-CHALLENGE
  
  This mechanism uses your account name and a randomly generated challenge that your client signs with a NIST256P elliptic curve private key.
  This mechanism is the least supported (Irssi [with a script] and WeeChat 1.2 [natively] are the only clients that support it as of this writing).
  This mechanism does not require you to be connected over TLS to use it securely (but we recommend always using TLS anyway).
  This mechanism does not require you to trust the server.

If you are unsure what your account name is, /whois yourself when you are identified; this is NOT the same thing as a nickname!

If you don't know what any of this means, but your client indicates that it supports SASL, just use PLAIN; it is no more insecure than NickServ IDENTIFY.

The Irssi script for ECDSA-NIST256P-CHALLENGE is located here.