Just a thought that occurred to me.
A while back somebody, maybe Storm, maybe JD posted what I thought was one of the most brilliant comments as a response to a strategy post.
He said "Stop trying to win so many hands."
One of the key skills to winning at poker is patience. The shorter-handed the games get, the less patient you can play other than being patient relative to your opponents. When you play HU, you can't be patient and you must by definition gamble more. Thus variance goes up, because good players play more hands, go farther with them and therefore suck out on big preflop hands more often.
Now, I'm not necessarily saying stop playing HU and go back to 6 max or full ring or whatever. Just be aware that by playing HU, you lose one of the edges you have over the competition; your ability to win by inaction.
FWIW, you couldn't get me to concentrate on HU SNGs as a standard game. There's already enough maddening variance in full ring SNGs for my taste.