Besides the above-mentioned problems related to ACLs and mode bits, you should be aware that a Coda client does not send data to fileservers when a running program calls flush(). You have to close() a file before it gets sent to the fileserver, and even then it doesn't happen if you are disconnected. After disconnected operation, you can't reintegrate without authenticating first.
For this reason, Coda may not be a good place to write log files. Commands like 'tail -f' don't work unless you are on the same client machine. A file being written by a process on one machine cannot be read on another machine until the writing process closes the file.