When I was in High School, we would all say Shema together, with trop. Since then, I’ve only seen this practice a few times; amongst a minyan of descendents of students of the Gra in Yerushalayim, at R’ Feldman’s shul in Atlanta, and a couple of other places. When learning Alei Shur this morning, I found this beautiful description of the value of the minyan reciting Shema as one.From Shir haShirim Rabba, translation mine:

“She who (fem.) dwells in the gardens, friends are attentive to your voice; let me hear. Flee my beloved, and liken yourself to a gazelle, or a young hart on the mountain of spices.” (Shir haShirim 8:13) When Israel enter the sysnagogue and say Qeri’as Shema (lit: the reading or calling of Shema) with concentration of thought (kavanas hada’as), in one voice, with a single thought and meaning, Hashem says to them “She who dwells in the gardens, when you call friends, I and My retinue are attentive to your your voice; let Me hear!” But when Israel say Qeri’as Shema with their attention cut short, this one earlier, that one later, and do not concentrate their thought in Qeri’as Shema, the divine inspiration flees and says “Flee my beloved, and liken yourself to a gazelle, a tzevi, the tzava, the army of above who give likeness to Your Glory in a single voice, in a single breath, on the mountains of spices, of besamim, of the shemei shamayim, heaven of heavens above!”