Double or Nothing SNG's have very little downswings..
Played around 40 so far, 4 sessions:
1rst: 8 UP, 2 DOWN
2nd: 4 DOWN, 6 UP
3rd: 7 UP, 2 DOWN
4th: 5 UP, 4 DOWN
The negative session are the ones where i lost a couple of pocket pairs, 2nd session lost 4 all-in's:
KKvsAA 2 times
QQvsAA
KKvs88
And still lost only 3 buy-in's.
I'm not saying that they are good because of my recent scores, made some decent results on regular sng's over 300 tournaments and i still think they are very swingy.
Let's see, 10 players, 5 double up, if we just play premiums, we are gonna get to 50/100 blinds with 7 players, max 8. Then we are down to 2 players out of money, 3 in. I don't really think there are large downswings here compared to normal sng's and cash game.
EDIT: I'm talking about mansion tournaments, pacific ones are turbos and can have a little more swings