We did a test with a laptop on each end connected to a pair of CL2300 units with minimal twisted pair connection between the two CL2300. The test was a ping from the 'local' laptop to the 'remote' laptop. The round-trip time was 8 - 10 ms. The default ping packet contains 32 octets.  In addition, the latency through the CL2300 is greater with a small packet than a large, because it's more processor intensive to put headers on the packet with only a little bit of data than with large packets.
Since the round-trip delay - let's take the larger number - is 10 ms, then one-way is 5 ms. But of course, that traverses both CL2300 units, so we need to divide that again in half to estimate the latency through the CL2300, which would be approximately 2.5 ms.