My company is in the process of upgrading the SQL Server CLR types that are being used with our software. After Googling around, I couldn't find a definitive yes/no answer to whether or not the SQL Server Feature Pack version can be greater than the version of SQL Server that's deployed.
The current release vehicle for that is NuGet, https://www.nuget.org/packages/Microsoft.SqlServer.Types. And this client-side package doesn't have any version dependency on the server-side version.