Zimun of 10 people

By a zimun of 10 people it is well known that we add "elokenu" to the birchas hazimun. I once heard over in the name of Rav Soloveitchik (maybe from Rav Chaim) that the idea of adding elokenu is to make the zimun into a davar shebikdusha (which of course requires 10 people). The reason why some people stand (by the word elokeinu) is because according to some minhagim, the minhag is to stand during davar shebikdusha (like kaddish or kedusha). This minhag is not universal, however. (For example, I believe some sefardim have the minhag only to stand by a kaddish that leads into another prayer which requires standing.) I also heard that R' Soloveitchik was opposed to people who "half-stand" up by the word elokeinu. Either sit or stand... but half-standing is neither here nor there.
In general, I have heard some interesting shittos from R' Chaim on davar shebikdusha. For example, I heard that Rav Chaim held that davar shebikdusha by definition is responsive davening, chazzan then tzibbur. For this reason he was more in favor of the tzibbur davening in a responsive fashion than all singing together.
I also heard that it was Rav Chaim's minhag to stand even during the kedusha of birchos krias shema (and I think Uva L'tzion as well) due to davar shebikdusha.