One thing is missing in this discussion that is asked in the question; the difference between NTLM and Kerberos.
NTLM is a properitary AuthN protocol invented by Microsoft whereas Kerberos is a standard protocol.
The big difference is how the two protocols handle the authentication:
NTLM uses a three-way handshake between the client and server and Kerberos uses a two-way handshake using a ticket granting service (key distribution center). In Kerberos the client must have access to a domain controller (which issues the tickets) whereas in NTLM the client contacts the server which contacts the domain controller.
The performance benefits, that SPDoctor talks about, are mainly due to the minimized amount of AuthN traffic between servers, client and DCs.
Also Kerberos are considered to be more secure than NTLM.
IMHO, it's worth the initial pain with Kerberos but make sure that you plan for it.