Kobo and Smashwords have a great relationship and Smashwords provides Kobo with daily updates of data for tens of thousands of titles. Authors who are comfortable using Smashwords are more than welcome to continue using their services. We like to advise that authors do whatever is most convenient and simplest for them.
Smashwords distributes to 8 different eRetail environments, of which Kobo is one, so authors are best to ensure that they keep their titles available to as many as possible. Their best option as a writer is to make their eBook available in AS MANY eRetail locations as possible for the largest possible reader audience.
The advantage of Kobo Writing Life over (or in conjunction with) Smashwords would be that authors gain direct control over their works in terms of pricing, metadata, availability etc. These updates will generally go onto our site much faster than they would through the regular Smashwords channels. They also have direct access to Kobo promotions if they qualify for our promotions tab beta test.
I hope that this has clarified this issue for you. If you require further clarification, don't hesitate to contact us.