I went from a triple CR to a double. Did not change out the shifters and only adjusted the limits a bit. Works great with Tiagr shifters. Can't really speak to the Sora.

I have found that a large rider and Sora front deraillers are not compatible due to the lack of strength of the Sora to hold position when power is on or you are hammering out of the saddle. There is just a lot of flex in that piece. My brother had that problem. Went to a 105 and problem went away and so did most of the noticable flex.