Let me completely rephrase my approach...

If you've ever installed the sql data model for ASP.NET that resides in
sql server, you'll notice that Microsoft has a table called
ASPStateTempSessions. There are two columns that hold the encrypted
session data of the user. These two columns are:

varbinary(7000)
Image

and they are each nullable. Depending on the size of the Session data,
one or the other column is used since Blob columns (such as Image,
Text, etc...) are inefficient. Using the Session in ASP.NET you'll
notice that it consists of strings only, so why did Microsoft decide to
use these types? Is there some effieciency thing? Or were they planning
on simply supporting possible binary data in the future.

-dave