In Mozilla's support forum (and elsewhere), Outfox responds to the accusations of malware:
https://support.mozilla.org/en-US/questions/981200
Outfox claims that the misbehavior of its product (taking over new tab settings) has been fixed and that the uninstaller in its newest version now really does uninstall thoroughly. They further claim that many of the sites offering removal help are scams that want to charge for removal. Those sites, they say, are spamming forums and blogs with false accusations using keywords designed to drive business their way.
One of the problems is that they are letting Outfox be bundled into other software packages (you know, the kind that install other programs unless you opt out using the sometimes hard to notice opt-out procedures), and it is being installed without the computer owner being aware. Naturally, when users see Outfox appear on new tabs, they freak.
The Outfox FAQ seems to offer valid ways to revert computers with the first beta installed back to normal. http://www.outfox.tv/faq/
I don't know any more than that. I have never tried Outfox.