I migrated from Seo Ultimate Version: 7.5.7 to WordPress SEO 188.8.131.52.
I used the seo data transporter.0.9.8 to convert the seo data from one to the other.
I however ran into an issue, and narrowed them down: its mostly FYI.
In SEO Ultimate: When I disable Permalinks - Remove "/category/" from category URL, it reverts back to original situation: all OK. When I however enable it in WordPress SEO, it seemed to break a page of mine, and I wasnt able to open the page, nor via renaming, etc...
-> I found out I had a category with the same URL (unused category though). Once I removed that, the page opened. If I didnt, I would have had to keep the Permalinks of SEO Ul. active.
You guys are doing a great job (the ones from Seo Ultimate too), and since migration from and mostly to your plugins will become very important for your business, I wanted to share my issues.