... The biggest benefit of this move would be not having to deal with VAT MOSS in the EU anymore. Total nightmare for tiny companies. The biggest drawback would be the trust situation with GCHQ and gag orders in the UK, because the company offers hosting services. So really, it's the plague or cholera.
However, the latter is possible to mitigate, because we're not using any physical infrastructure in the UK anymore these days. That was already a consequence of what they did to the Guardian and others back then.