birchos kriyas shema and tefilah b'zmana

I should mention with respect to R’ Chaim’s chiddush re: saying brachos kriyas shema b’zman being more important than tefillah b’tzibur that the Ramban writes that part of the celebration of “mikraei kodesh” involves gathering together for tefillah. One might argue that the enhanced kiyum of kriyas shema with its brachos should not outweigh the Ramban’s kiyum d’oraysa of tefilah b’tzibur on Shabbos and Yom Tov. I don’t buy this approach. Celebrating the day as “mikraei kodesh” is a chovas hagavra, not a din in tefillah; reciting birchos kriyas shema is a din in the definition of the mitzvah of shema. One can fulfill mikraei kodesh through some other means during the day, including by davening other tefilos b’tzibur, but one gets only a single chance to properly fulfill shema.