I never understood why the orbs don't hurt the one firing them. All other weapons potentially can hurt you (even the mag I guess

). Maybe Valve figured noobs would kill themselves too often, never getting into the game.
And speaking of noobs, the more of them on a TDM server, the worse it gets if you have ff on. So, for most players I guess it becomes a difficult transition from ff off to ff on, if you ever do it. Much to my surprise though, I've seen my kid play on several coop server with ff on. Can't see see the meaning of that.
I've always advocated the use of all weapons to their full potential in this game. And I use spam whenever I see the need for it. However, even with ff on, a lot of European clans whine about the use of spam. Certainly, lostvillage and biohazard centers around who can control the rpg even with ff on. Lockdown not so much, but the better the player, the more use it has. ChocolatePeanuT if anyone has shown that the rpg has qualities beyond a mere noob weapon.
Using ventrilo I cannot count the number of times we've asked for a green go to fire that orb to clear certain areas out. It's by all means not rendered useless just because ff is on. Yes, you get teamkills now and then, but everyone's aware of that, so nothing to get upset by.
So, I like how ff reduces the domination of the spam weapons. And I like how it forces you to communicate more, promoting the team that does that part best. But maybe there's a limit around 4on4 or 5on5 where it's simply too cumbersome to keep track of all your teammates in order for spam to be really useful. FF on still seems more intuitively natural to me.