I updated a Surf SOHO hardware version 1, from firmware 6.2.2 build 1790 to 6.3 build 1967 and enabled the new DHCP logging feature in 6.3. While running 6.3 I did see a couple messages in the log about the router giving out an IP address. Then, when I rebooted back to firmware 6.2.2 the DHCP messages were no longer in the event log.
Not the biggest problem in the world, but it does seem like a problem. Unless each firmware gets its own copy of the Event log? It seems not however.