Question:
Should one who follows customs of Eretz Israel wear a kittel at the Pesah Seder?
Answer:
1. I can think of no reason to wear a kittel at any time during the year.
2. On Yom Tov one should wear one's finest clothing - see Rambam's MT Yom Tov 6:15 and Shabbat 30:3. If this is too uncomfortable, one may wear whatever is appropriate. The main thing is that one's attire on Shabbat and Yom Tov should be noticeably different and finer than during the week.
14th of Nisan, 5771 Sunday, 17 April 2011