It's a bit risky, yes. But Kaveri was never late at MAS whenever I traveled ( or may be I got lucky :) ). At least for MAS-SRC and Coromandel, it was more or less a reliable connection. But if the other 3 weeklies are running on the day, then they will always be the easier, less risky options.
Of course, given the mail's sleep-killer run, might as well travel in UR if tickets are not available. There won't be any sleep even if we get a berth. :P