I don't buy the whole Joel Spolsky theory that you should never throw away working code. Sometimes the existing code is written with assumptions that no longer apply, and removing those assumptions piece-by-piece -- or even discovering what those assumptions were! -- is just too difficult. It's a moot point though, given the amount of work it would likely require. I'd be happy to see PerlMonks drop lots of features that I consider bloat, but every feature seems to have some individual who swears they can't live without it.

I'm not sure that migration to Everything 2 would be helpful either. Whilst it would make it easier for individuals or groups to set up replications of PM, there would still be a whole lot of customisation in the core, and sensitive data that would be impossible to share openly and very difficult to mock up.

Everything2 has moved the code out of the database and into CVS (at least that's what chromatic told me in another thread), and that's a major structural improvement. Hopefully it provides a better approach to customization as well. As for the difficulty of creating test data, everyone always has an excuse for not doing this, but it's important. Creating test data would mean that developers who don't have access to the live PM database could actually test their code!

The gods would still need to inspect for backdoors and malicious failures and test to their satisfaction

If everyone could download and run the code easilly, then everyone could help with this too.

The only way I could see of alleviating the bottlenecks in the testing and approval mechanism (...) is to make it possible for PMdevers to test their own code in a realistic, but non-critical environment

With access to the code, an easy install, and a test suite, anyone's laptop could be a realistic but non-critical environment.

Your idea might work as a stopgap measure, but I don't think it addresses the real problem, which is the difficulty of contributing substantial well-tested code.