@bazzoka and @Chris83:

The newest version of the standard Arduino Ethernet (2.0.0) now has built-in support for the W5500 (in addition to W5200 and W5100) modules.
This eliminates the need to pull in the Ethernet2 library and change the sketch code to build an Ethernet Gateway with the newer/cheaper/better W5500 modules.
Supposedly it also has some substantial performance improvements as well (see here: https://www.pjrc.com/arduino-ethernet-library-2-0-0/).
The only downside I have run across so far is the increased progmem flash size that makes the sketch about 2.8 KB larger.