It may be coincidence, but I've never worked for a company that uses text files for logging or auditing - always table driven. Personally, I'd never use text files for similar reasons that I'm not a fan of using .raw files. Everything should use tables IMO. The person above makes a good case for the possibility of text files, but most DW troubleshooting is done by the developers and I just couldn't imagine using text files vs the ease of querying a table. Kimball has a nice auditing framework that provides the basics - for free. I've seen a lot of companies use this as their base and then expand upon it.