I can’t really compare how much faster, safer and reliable is r2-6.1 against Ubuntu’s 5.5.
The story about why Debian not packaging r2 is complex and long (several maintainers disappeared without notice).
They decided to remove the package after me rejecting to backport fixes for a 4 year old copy of the project to address some CVEs. CVEs usually are a 5% of the real issues for projects like this, just git log|grep crash for a full list.
I refuse to maintain abandoned software that’s not even distributed in its pure source form. Debian ships custom patches that are never reported upstream.
Ubuntu keeps shipping a the last version packaged by Debian, for an unknown reason. Almost no modern plugins like r2ghidra will work.
I have good conversations with Debian maintainers and their release cicle won’t fit what r2 users would need. We move fast, debian expects stability over time, both approaches are fine but unfortunately incompatible.
I did huge advances in r2 about perforance, stability, code quality and security. But its a huge codebase and two hands and two eyes can’t do as much as I wished, so still, after 20 years I recommend everyone to use r2 from git if possible