Here we are; Steven Ovits (thanks!) pointed some documentation to me.
Short version: TEXT and NTEXT are deprecated since SQL Server 2005, but they still work today. Instead, they suggest to use VARCHAR(MAX) and NVARCHAR(MAX) - yes, with this exact syntax; they have a hard cap of 2GB for field.
Performances are OK.
I gladly leave to you the decisions about what/how to support. :-)