I would most definitely be for this holiday to be added to the Jewish calendar. A Jew should grab at any opportunity that would enable him to repent and become closer to HaShem. From JPost:
Hundreds of members of the Ethiopian community signed their names to a petition Thursday calling for Israel's religious leaders to incorporate the annual Sigd festival in the calendar of religious Jewish holidays.
As in previous years, Ethiopian Israelis young and old, Israel-born and new and veteran immigrants were bused from around the country on Thursday to Jerusalem's Haas Promenade to mark the ancient holiday, whose name means "to prostate oneself in worship" and is meant to renew the covenant between God and the people of Israel. It is normally celebrated 50 days after Yom Kippur, on the 29th of the Hebrew month of Heshvan, but was held two days early this year because the date fell on Shabbat. The community's spiritual leaders, or Kessim, recite prayers in the Ethiopian Jewish language of Gez calling for the return of all Jews to Jerusalem.
The drive to have the holiday made part of the Jewish calendar was initiated earlier this week by the Israel Association of Ethiopian Jews, which sent its request to Sephardi Rabbi Shlomo Amar and Ashkenazi Rabbi Yona Metzger.
"There have been many festivals over the years that were started in the Diaspora but were eventually incorporated into the cycle of Jewish holidays by the rabbis of the time," said association spokesman Avi Masfin. He cited Hanukka and Purim as holidays that were established by particular communities and later adopted by all of world Jewry.