It allows you to use a CM4 board which features a quad-core ARM Cortex-A72 processor (faster than a quad-core ARM Cortex-A53 RPi3/THEA500 Mini spec CPU), it will come with an optional 'break-out' board to send the Ethernet, HDMI and USB to a port to mount on the A1200 Expansion Port (improving airflow compared to full size RPi boards) and best of all the Emu68 software compatibility issues with CM4/RPi4 has been solved in the week proceeding this hardware release meaning there are basically no negatives! Finally, CM4 Modules though still difficult to source, are more readily available and cheaper than the comparable RPi4!
Note: Current RPi4 revisions are June 2019 technology and the CM4 was released in late 2020 (compared to 2018 for the latest RPi3A+ revision). We are overdue a RPi5 at this point in all honesty! We might as well support the latest revision of the RPi4/CM4 and squeeze what we need for Amiga CPU emulation out of it IMHO!