I helped make a list[0] (which is still kept current) of OpenWrt and dd-wrt hardware a while back. You might want to give OpenWrt another chance, it may not be as outdated as it might seem.
I used to run my customized build of OpenWRT on an old, passively-cooled Pentium II box. It ran completely from ramdisk and had all configuration baked into this ramdisk image so that the noisy HDD could be powered down immediately after bootup. This was before the era of cheap small SSDs.
The official builds support installation on disk partition just like any other Linux distribution.
[0]http://rooftopbazaar.com/routerfirmware/