you are way above the 14-16 fl that is the rule of thumb for a black room. I would not worry about 1 vs 1.1 but more about which screen has the most complaints as for quality here in the forum. Then buy the one with the least!
1.0 to 1.1 does not make a lot of difference. So I would go with the screen that had the smoothest surface. I do not know how smooth a Grandview is, so I could not recommend one over the other. Besides, I would not be surprised if the gain was not the same.
Thank you brother, i live in turkey we dont have many screens here. My only dubt is will i have problem with 24fL on my 106inch fixed frame screen? my room has dark grey walls and ceiling. The projectorcentral calculator shows to me it ll be 24fL