The approaches are more similar than you think. At least the parts you mention Experimental XEPs let people experiment. The compliance suites provide a single spec controlled by a committee. And the differences don't matter when the user experience is the same.
XEP-0027 OpenPGP has been officially obsolete for Matrix's entire life. XEP-0374 OpenPGP never went past experimental. It was officially deferred 3 years ago. OMEMO is the only proposal active.
The compliance suites tell you what you need for file transfer. Core requires XEP-0363 for file upload. Advanced requires XEP-0234 and XEP-0261 for direct transfer. You can ignore the experiments.
Figuring out what features 2 clients share can be confusing with either protocol. Looking at Matrix's clients matrix[1] is easier than finding a list of XEPs for each client. But you still have to figure out what the server supports and what it doesn't have to.
The real difference is how 1 company dominates the Matrix ecosystem.
XEP-0027 OpenPGP has been officially obsolete for Matrix's entire life. XEP-0374 OpenPGP never went past experimental. It was officially deferred 3 years ago. OMEMO is the only proposal active.
The compliance suites tell you what you need for file transfer. Core requires XEP-0363 for file upload. Advanced requires XEP-0234 and XEP-0261 for direct transfer. You can ignore the experiments.
Figuring out what features 2 clients share can be confusing with either protocol. Looking at Matrix's clients matrix[1] is easier than finding a list of XEPs for each client. But you still have to figure out what the server supports and what it doesn't have to.
The real difference is how 1 company dominates the Matrix ecosystem.
[1] https://matrix.org/clients-matrix/