You need to honor / compare converter latencies.
FF800 is an older design as waedi already told you.
Here some additional information about converter latencies from manual ch 30.2 latency and monitoring at 44.1 kHz:
AD: 43.2 samples = 0.98 ms
DA: 28 samples = 0.63 ms TOTAL=1.61ms
Newer products like the UCX II have the following sample rates:
AD: 5 samples = 0.11 ms
DA: 6 samples = 0.12 ms TOTAL=0.23ms
This alone makes a difference for converter latency of 1.61 - 0.23 = 1.38ms.
Then next point is that both manufacturer might have a different idea about stability.
As you can see in the RME manual, RME adds a safety buffer for Apple's macOS where audio has to pass the sound libraries of Apple. You do not have direct access to the recording hardware like with Windows and ASIO drivers.
At the end of the day it can't be faster than "fast and stable" ...
But there are many other manufacturers / products where the latency is much higher compared to RME (and Motu in this case), up to double the amount of time.
Another advantage of RME compared to Motu, the internal FPGA is performing the I/O and can be re-flashed in case of an error. Motu uses 3rd party communication chips where a such a re-flashing is not possible at all.
RME has the better overall design and is in many details better compared to Motu.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14