Actually, to be 100% safe, you should only add Extras and download from the application manager, not from downloads.maemo.org; I'm almost certain though that packages listed on downloads.maemo.org only link to sane repositories, so yes, most probably you could try those, too.

You see, the problem with those "wild" repositories is that nobody checks for consistency. A package in repository A may depend on a certain version of a file that used to be in repository B... and everything worked when package A was created and uploaded. But meanwhile, repository B may be down or offer a different, incompatible version of the file. Etc etc....