After long time and not to say with after giving up my thought of setting up nexus/artifactory/archiva I came back to same stuff recently around month back.
I restarted my exercise with nexus 1.2.1 and to my surprise with very little efforts I manage to get it up and running for Apache projects I care about which are CXF, Servicemix.
I also upgraded our team nexus repository manager from older version to 1.3.1 and happily using it now. It is lot more improved than I thought it would have been. In past I was very much annoyed when my pom files got corrupt for the artifacts that were present in more than one repositories I had configured but it appears to have been fixed now and also the web interface for configuration is very helpful.
Having said all this I did spent some time today in figuring out why the artifact present in remote repository won't download even though I had it configured it correctly. After a lot of head scratching and looking at the configuration multiple times discovered that there is a parameter on each repository you configure called Not Found Cache TTL which by default was set to 1440 Minute once I changed it to smaller amount like 2 minutes my build went ahead happily.
I am overall very happy with the new Nexus Repository Manager (surely much better experience than I had with proximity and old nexus version).