title: Differences when convert between Geometry & Geography instances
body: <p>Using SQL Server 2008: assuming I have a valid geography object <em>geog1</em>, converting it to a geometry instance <em>geom1</em> (using the same SRID) and converting it back to an object geography <em>geog2</em> shows no difference between <em>geog1</em> and <em>geog2</em>.</p>
  <p>However, due to a problem already discussed <a href="https://stackoverflow.com/questions/1163925/sql-server-2008-geography-linestring-size-limitations">here</a> I cannot create a geography object containing a linestring from my original data. It works with geometry objects. However, if I perform a <code>MakeValid()</code> on the resulting geometry, I can create a geography object again.
  The problem is that I don´t know if this geography will be much different compared to the original linestring that was not accepted by <code>geography::STGeomFromText()</code> before.
  Especially the object length (<code>STLength()</code>) is of interest to me.</p>
  <p>Does anyone know if the conversion between geography and geometry types is losless and if a <code>MakeValid()</code> call on a geometry changes the data (especially when it comes to length)?</p>
  <p>Thanks</p>