I was thinking something along the same lines as Bob.
If you are proficient with skis, they might help you -- in some places. But there are so many places they would just be a burden: any steep descent, where there is a zig zag trail. skis just don't work there.
Going up, skiis aren't any faster than hiking ...well, maybe a little better if the traction for boots is bad.
Skis are great in wide-open terrain, when it's flat or even better when you have a light to moderate descent. But in the Sierra, those ideal areas are limited, maybe even few and far between. So any advantages the skis have just don't match up to the extra weight to carry over the distances where they couldn't be used.
They would certainly be useful if travelling the Sierra earlier in the season -- late winter, for example, but by now, not so much. I've hiked many miles over consolidated snow in spring time/early summer. It isn't noticeably slower than hiking on a dry trail.
