Just to pick up Axel on a couple of points (since he's not an Alfresco employee he's not aware of what testing is and isn't carried out). Aikau has an automated test suite with approximately 80% code coverage (and the 20% that isn't currently covered is largely non-production code). This is actually the highest automated test code coverage within Alfresco so in that regard Aikau is exceptionally well tested… does this mean that there won't be bugs? Of course there will… however, each time a new bug is raised we create a new unit test to reproduce the problem, fix the bug and that way we prevent regressions of that particular issue.
We also prioritize bugs above all feature work, so if a bug is reported it will be included in the next weekly sprint which means that any bug you raise will be fixed typically in less than 2 weeks. Compare that with a bug that might be found in Alfresco Community and you might be waiting up to a year for a fix, or with Alfresco Enterprise that you could be waiting a few months for the next service pack (unless the issue requires a hotfix - in which case you would get it as soon as it is resolved).
We do hotfix releases of Aikau as Share goes through the QA process so a version of Aikau that ships with a release of Alfresco could be considered more robust than others. So if you upgrade to a newer version of Aikau and there is a problem you can easily revert to your previous version, report the bug and then upgrade again when that bug is fixed.
It's obviously not wise to update Aikau on a production system for the sake of it, but we would expect people to test any customizations they've made to Share using a newer Aikau release before they put it into production.
Finally, there will always be bugs… if you find them, report them and they will be fixed… but if they're not reported, there's not much we can do about it.
