I use this approach and I personally think it is a much cleaner method. Having said that, I sometimes have support staff who try and nudge us in the opposite direction "Hey, let's put actual signatures on the SOP itself", but it is usually due to a difference of opinion, nothing more, and nothing ever materializes from it because they cannot demonstrate the efficacy of signing on an SOP when they are already required to sign a change request form that is designed for that, plus traceability.
Brian