I was evaluating Shopware 6 as a replacement for Magento 2. Even looking at the paid edition it lacks some serious features.
While the platform has a lot of good things going, the most important part is what is keeping it back from being a usable platform when you sell to more than one country.
The problem is of course TAX.
The tax rules in Shopware 6 are very basic and do not cover all the cases you need when selling within and outside EU.
You can set up a store that sells domestically pretty easily with fixed tax rates, but once you start configuring for zero tax rates for countries outside EU you run into major problems.
There also does not seem to be a way to set up tax rates for shipping costs which are very weird. Maybe I just missed it.
Hopefully, they can solve these issues in 2020 and we are interested in this platform again.