I don’t have experience withe 7911 but I have worked extensively with the 7940 and 7960 for the Cisco phone configuration options on our IBeX (http://www.finite-tech.com) system.
The bottom line in my opinion is that SCCP is great if you are using Call Manager and it is taking care of most of the work. SIP does a much better job of integrating with Asterisk and in the long run if you use a system like IBeX (or others) or you figure out the configuration files for the Cisco phones you will have access to a number of features and can integrate these with Asterisk.
Don’t get me wrong SCCP will work with Asterisk, I just don’t have much expereince with it and I think you will find more people running SIP any more than SCCP.
Converting your phones to SIP is quite simple and once you get everything setup you can do a phone every couple of minutes. I do this from my laptop using Pumpkin TFTP server, a small switch and a DHCP server on my laptop (usually Linux running on VMware) to get the phones booted.