You are likely seeing dated references. Based on the percentage of valid email my server receives from servers using SPF, the consensus is to use SPF.
I heartily recommend setting up SPF. Setup records for your MX allowing it to send email, as well as for the domain you use in e-mail addresses. For domains that don't send e-mail setup SPF to indicate that.
I find SPF records for the e-mail server more helpful and reliable in blocking Spam than those for the sender's e-mail address.
If your server supports SPF records configure them in addition to TXT records. If you change your configuration there may be a little overhead in keeping the records in sync, but many systems can configure their SPF so it automatically adjusts to MX and address changes.
You may want to review my post on Securing your Email Reputation with SPF. My first implementation of SPF was to block a spammer who was forging a domain I provide email services for. Despite relatively low SPF penetration it was very effective in shutting them down. However, we still get spam to the forged address they created. (Its a great way to verify spammers as only spammers would use that address.)
I believe penetration of SPF on the receiving side is likely greater than on the publishing side.
EDIT: If you do use SPF records, make sure that people delivering automated mailings are aware of the requirement to get their servers added. (The server should be fully vetted as automated systems are often poorly configured and may have a profile similar to a spambot. It isn't that difficult to set the server up correctly.)