From our side (cloudControl) there rule is that latency critical Add-ons have to be in Europe and optimally in the same EU-West AWS region when they leave beta status.
Usually you can always "buy" services directly and still use them in combination with our platform. The only difference is you won't get a consolidated invoice and cloudControl first level support mostly can't really answer questions regarding third party services not bought via the add-on market due to lack of information.