Well, it wasn't easy for me. I did it back when the first letters first came out at the end of August, and have dealt with a huge fiasco of double accounts for weeks. It has finally sorted out, with my sales data finally coming back on line for current sales mid Oct. But I have lost all my sales data on my dashboard going back to when I first started self publishing in 2009. The Zon did send me a excel print out of all my sales when I asked, because legally they have to keep track and I claimed all the sales on my income tax. But it all doesn't show up in my dashboard anymore or on the nice little graphs.
But as usually in Self-Pub, deal with the changes, adjust, and keep moving on with writing, publishing, repeat.