I would first consult the update revision history if you can find it available - this may make mention of anything (un)important to you. Sometimes it is often best to not update until you come across an issue. Partitionmagic is not the type of software which could introduce vulnerabilities if it was not kept up to date, so if the version you have is working in your environment, there may not be any actual motivation for you to have the latest version, aside from the fact that it is the latest version.
I too also occasionally update things for the sake of updating them, however I cannot say I would recommend it.
Depending on how bad you would like to perform this update, you might find that removing SP2 resolves your update issue.