Situations like this are usually best answered by just giving it a go. See what happens and report back. We'll all learn something.
I have seen undergrads freeze pelleted e. coli cells in a -20 with no cryo or buffer and they grew back up just fine.
The only times i get concerned about the quality of my cells is if I'm doing a transformation after some sort of cloning (mutagenesis, ligation, etc.) or expression (I usually like to use freshly transformed cells for expression rather than a frozen stock, though this isn't always critical).
Edited by labtastic, 13 March 2014 - 05:34 PM.