Well, my personal experience is that Lone Wolves aren't worth it anymore. Now, there are still one or two roles where i noticed that Lone Wolf can be worth it, mostly for the extra HP and ability points but in most situations you will always benefit more from having 4 party members rather than 3 or 2.
Of course dual Lone Wolves can still beat the game so if your into it for the sake of having them or roleplaying or whatever reason you have, go ahead, just that they aren't optimal anymore.