There are several fields on project import pages so "URL Name" should be "PRODUCTNAME URL Name" so it's clear that field is for the destination.
We should include extra notes on all the specific importers (both project & individual forms) regarding their caveats. These come to mind:
- google code: home content not imported (its not part of the wiki)
- google code repo: if project has multiple repos, only one is imported
- google code tickets: private tickets not imported
- github wiki: no wiki images or internal files, syntax for .rst and some other formats not supported, see https://sourceforge.net/p/allura/tickets/6534/?limit=10&page=1#2467