Posting this as more of a warning. I upgraded my private account this week to business. I then noticed that all my sales were being charged a final value fee of 10.6667% regardless of the Headphones and E-reader categories which should be charged at 6.9% per Ebay Fees. Spent hours on phone with support who were as confused as me. Escalated call to senior rep and received credits for 2 of the orders and a ticket was raised with the development team.
A day later (more sales still charged at 10.6667%), response from DEV team came through. The actual quote "According to development team, if the user is private seller at list time and Business seller at sale time, then the user gets charged as a private seller for the order and they get a higher rate."
In other words, re-list everything for correct rates to kick in. I did this and it solved the issue with sales after that. I then requested credits for the overcharged sales which was declined. So, if you are planning to upgrade or have upgraded to a business account, check that you are paying the correct rates.