A friend of mine who plays in tourneys regularly also despises re-buys because he has been knocked out of the money a couple of times by players he knocked out earlier who re-bought and came back. I've empathized with him in these instances but argued that he's going to profit in the long run with re-buys in place. The weaker players in the tourneys will generally play more loose early if they have the security blanket of getting back in if they bust out. Besides, more money in the pot is always a good thing, right?
My personal preference is re-buys that are limited to a certain point in the tournament (say, the first 60-90 minutes or the first "x" blind levels) because I think this promotes the main advantages I noted above -- encouraging looser early play (allowing savvy players to build chip stacks early) and juicing the prize pool.
I'd be curious to hear opinions about add-ons. I have never played a tourney with them (admittedly I'm a tourney noob, so I'm sure it's just a matter of time), but my initial instinct is to be against them. From hearing others discuss it, an add-on is almost guaranteed to get every player taking it, just so that a player doesn't instantly have a chip disadvantage, relative to the players who take the add-on.
If the motivation behind the add-on is to juice the pot, why not just increase the buy-in? I can see the advantage of an add-on if you're surviving in the tourney but short-stacked, but the advantage is nullified if all your opponents also take the add-on, right?
