Has anyone successfully used the wordpress importer option for SS blogs?

We have a client who has a rather extensive blog on WordPress and wants to move her blogs to SS. We haven't done this yet and I'm trying to figure out how much work this is. She has about 1000 blogs which seems insane so we might want to cut them off to be the last 2 years worth of content. Can anyone weigh in on how much work is involved here to keep the same URL string, etc? and uploading images?

Thank you!