an nzb is an nzb....it will work regardless of which provider you choose, as long as they carry the group hosting the file, and your retention is good enough. most providers are reaching 1000 days retention, and im not sure very many ISPs even provide access to newsgroups anymore (if they do, it sucks).

as for finding files, there are plenty of search engines, and headers to create your own nzbs, so you never even have to use a different site.