Ignore the uninformed masses.

Although this is useful information, gratuitous displays of hubris are gross. You should do yourself a favor and keep reading - it is clear that the decision should be up to the user after careful consideration.

All of the issues in regard to testing have well known mitigations which are trivial to implement. You can find this information and the corresponding links here

It is a good idea to include unstable and experimental in your apt sources so that you have access to newer packages when needed. With the APT::Default-Release apt config setting or with apt pinning you can have packages from testing by default but if you manually upgrade some packages to unstable or experimental, then you will get upgrades within that suite until those packages migrate down to unstable or testing. The apt pinning needs priorities lower than 990 and equal to or higher than 500 for this to work nicely. You can also pin some packages to unstable/experimental that you always want the latest versions of.

It is a good idea to install security updates from unstable since they take extra time to reach testing and the security team only releases updates to unstable. If you have unstable in your apt sources but pinned lower than testing, you can automatically add temporary pinning for packages with security issues fixed in unstable using the output of debsecan.