Is it okay to upgrade the AEM with 6.5.5 service pack and keep the artefacts compiled against 6.5.0 itself. We tested functionally and there are no issues. Is there a mandatory requirement that all artefacts on the instance needs to be compiled against the same version.
In many cases this approach works. But there are cases, where API changes are introduced (typically for security reasons), which make bundle imports not working anymore. But that's something you can find out very easily. But evn in that case I would suggest that update to the matching uber.jar asap.
An unobfuscated version which can only be obtained by licensed customers and partners through Adobe Support.
There are a variety of cases when youneedthe unobfuscated version – certain types of unit tests, certain Declarative Services use cases, etc. These are laid out in thedocumentation. If you were using the obfuscated version before, you can continue to use the obfuscated version. And if you needed the unobfuscated version, you still need it.
I would recommend to go with exact uber-jar version matching with AEM. Adobe recommends deploying against the Uber Jar that ** does not**contain the deprecated APIs to make sure that your applications will run properly on future versions of AEM.