Operating under the principal of "If it works, don't change it", we (that is, my place of employment) are still running on 5.005_03. We have reached the point where there are useful-to-us modules requiring 5.6 or higher, and are looking into upgrading. While travelling without a map may be an exciting adventure, I'd prefer to know what issues, if any, we're likely to encounter. Primarily, what might break in our current codebase? The changelogs are somewhat less than useful, having a rather low signal-to-noise. Since many people have traversed this route, surely some have written of their trials. Or will working 5.005_03 code Just Work under 5.8.0 in all case, if the necessary modules are retained?