You should go for the basic version which you can also upgrade later. If your into simple basic recording the Studio versions of Sonar are plenty.
Your right that most of the extra cost for the Producer version is the fancy stuff that when I look at the list I would never use it.
By the way there is also an X1-2 forum now which the majority of members here now post on, this is the old forum and is pretty quiet now.
Your going to want to buy the audio interface at the same time as Sonar just does not work properly at all with out one and ASIO drivers.
Good news is I think most Roland interfaces also come with Sonar. Might be the way to go, they make a decent interface.