Basically, the reason why my Lost World victories were less than my others are two:
1) I didn't met many LuxChomp w Dialga (where you CANNOT win through Poltergeist) but i met many with a Darkness Tech (where you CANNOT win through straight Gengar Prime if your start isn't good)
2) Out of 19 games, 11 were in Top Cut
I personally think that in Top Cut a straight Lost World deck is always gonna lose.
I had several top cut games which were played REALLY fast on both sides and the 60 minutes finished when we were finishing the 2nd game.
The problem is that in Top Cut you lose so much time in shuffling/setting for the 2nd and the 3rd game (4-5 minutes) and in thinking at the board and about when/if it's better to scoop.
It's easier to finish one game in 30 minutes + 3 turns than two games in 60 minutes (which are always 50-55 minutes of play) + 3 turns.
This is why i feel that a deck like LostGar, if it wants to win, it has to have a way of winning through prizes.
The reason why i didn't play 2 SF or 3 SF is just one: if all you can do is Poltergeist, you'll autoloss to everyone's LuxChomp, at least in the Swiss games. Winning through Lost World is much easier.
I wouldn't change a single card of the deck after my tournament, if i could.