Have both 405cx and 310xt. Both have been great bits of kit. The 405 does have a few issues, but still very useful. My first one locked up after about 12 months and was replaced after I retuned it to Cotswolds. Also a few gliches occasionally and the bezel issue, which for the most part is solved by locking it. 310xt, I've had no problems with but I've used it only for 6 hour plus runs. L50 and Bullock Smithy, it lasted for the full event. I guess it depends on budget to a degree. 405, I think, is available very cheap on e-bay, but I'd like to know there's someone I can return it too.