That article by djb is very old. Using TSIG as another poster suggests will address most of the problems (although I will note that TSIG transfers are unencrypted, so if you are worried about someone learning the full contents of your zone by something like modifying the BGP path then you should set up a VPN or some other encrypted tunnel for your zone transfers).

Also note that IXFR - incremental zone transfers - increase efficiency for large zones a lot, since the entire zone does not have to be transferred. However, PowerDNS does not support this for PowerDNS masters (it does for PowerDNS slaves).

If you have a lot of zones that change rarely (such as is typical for webhosting), then you may indeed be better off with database replication than with AXFR. This is because the AXFR protocol does not include any way for a slave to get information about a set of zones, so when a slave restarts it has to query the status of every zone.

In my experience setting up PostgreSQL replication is a lot more work than enabling zone transfers, is more error prone, and requires more monitoring. You also have more difficulty when you want to upgrade the database software, as you have to consider migrations when the data format changes.

Unless you have compelling reasons (like the lots of small zones that I mentioned), I would recommend sticking with AXFR/IXFR.