A major difference is that if you have a view which uses that varchar(50) column, you'll have to drop and recreate the view in the same transaction that you inc

A major difference is that if you have a view which uses that varchar(50) column, you'll have to drop and recreate the view in the same transaction that you increase the length of the column. (And if that view has any dependent objects, you'll have to do the same for them.) With the text type and check constraints, none of this is necessary.