My experience is with small stakes so im not sure how applicable it is because at the end of the day my poker bankroll is easily replaceable (<$400).
I'd not had any noteable cashes in tournaments i.e. my best was about $180 for 1st in a turbo on partypoker and i also had a few >100 cashes in <$10 tournaments.
The stars SCOOP came on and after some pretty consistent 6 and 11 dollar SnG bankroll building i decided to have a flutter at the small stakes main event ($109(?)) and cashed 2.5k for a disappointing 46th.
This was the biggest tournie ive entered online and i actually found i played so much better and was able to concentrate for the full 12hrs because i was staking such a disproportionate amount of my roll to normal and didn't engage in the usual distractions (pokertube/tv/music) plus i felt 'in the zone'
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I'd also agree with some of the above comments about bigger fields, there was definitely a large amount of seriously awful players, perhaps taking shots as well, similar to the standard you might find in the $3.30 rebuy.
I'd say it's worth it for the potential reward but make sure you don't commit more than you can face losing from your hard-earned roll.