Interesting question, in Europe they have different versions available, some even without the systainer. On the festoolusa site I can only find one version.
BUT from what I've read here is that with most dealers, you can order the saw with a different length guide rail, and only pay the difference extra; so it would be logical that you can order the saw without the guiderail and get "the difference" discount.
Allthough, I believe that in Europe, if you get the set version with the rail, you pay less than if you would buy it seperately, so the discount might be lower than the value of the rail. Example: In the Netherlands price difference between the version with and without guiderail: 27 euro's; price guiderail seperately: 88 euro's.