I know, it's cheap to paraphrase a well-known writer. However, it doesn't make the question less valid. Usually the migration to a new major release of a software product is quite an undertaking. This is certainly true for Oracle SOA Suite 11g. That said, there are more than enough reasons to go for 11g, as it delivers a whole lot of new functionality that you might need. That new functionality is not the subject of this post, but you can find any information you need on OTN.
What I expect to see happening however, is a limited amount of back-porting of 11g functionality into the current release (going for 10.1.3.4 or even 10.1.3.5). So, depending on your needs it is imperative to have a good look at your current and future situation, to determine what will be the right strategy for you to take. Don't hesitate to contact me if you have specific questions about the way forward to 11g.