Another option you might consider is Google Analytics App+Web.
It is a new type of Google Analytics property which is event-based (like Amplitude and Mixpanel). In App+Web you can collect exactly the same data and in the same format as the other 2 tools mentioned.
The great things about it are: - it is free - there is a free integration with BigQuery (though you'll need to pay for BigQuery, but for most SmB's it is peanuts - $5-30 a month)
Not so great: - reporting side is pretty buggy (App+Web is very new).
So if you are ok building your reporting in something like Google Data Studio, App+Web will be a great option. Your data analyst will especially be happy to have all the data in SQL format (BigQuery).
If you choose App+Web, then you can use Google Optimize (also free) as an A/B testing solution.