Hi,
Yes, it's pretty much all the same with OpenWRT, except the packages, some of the packages may not work or could not be found in opkg list because of openwrt versions. So everytime you try to install anything check the version. RUT2 and RUT9 should support everything until Chaos Calmer version, and RUTX and TRB devices should be up to date to use anything. Regarding documentation of configuration and other changes that can be done on OpenWRT - they will also be possible to be done on RutOS.
EB.