scp with crypt-type = none: Safe or not?

[Roy S. Rapoport]

I've got a user who would like me to enable encryption type none so
they can do faster file copies via scp.  

The files they're copying are not sensitive.  My concern is whether
or not using encryption type none will geopardize the actual
session and make it more vulnerable to hijacking or make it easier
to attack the host.

Thoughts?

-roy