Ah, thank you. The mailing list archives were inaccessible, so I couldn't
see whether anything related was committed. I've just gave it a try and it
works well for IPv4, even with ACPI enabled, which it wouldn't so well on
NetBSD due to watchdog timeouts from time to time. IPv6, however, doesn't;
anyone interested in adding support could perhaps check
http://mail-index.netbsd.org/tech-kern/2007/03/18/0003.html. The diff
attached there fixed the IPv6-problems, apparently also for other new
rtl8168-variants (but the changes are quite big, I'm afraid).