I think so compared to a non-GB of similar weight and weave. But the softness of GB like any other fabric is dependent on a variety of factors aside from the yarn itself including weave and finish. For example, I have felt lightweight escorial flannel that feels soft and limp and I have 650 gm escorial coating that is relatively firm and hard.
Alumo and Bonfanti are my go-to fabrics. In particular, I like the Alumo 3-ply, although it is offered in a limited range of colors and last I looked, in no patterns. I also like D & J Anderson sea island very much. I'm surprised to hear that Riva is single ply. Are you sure? As far as I know, Bonfanti's fabrics are all 2-ply.
Fyi, Bonfanti's Capri range is a 120's poplin and sells for 21 euros/meter. Its Bristol range is 80'sx120's poplin and sells for 19 euros/mete. Both are woven on a 90 cms. loom. I like the Capri a lot. I also like the Bristol but you have to account for more shrinkage.
I really don't intend to be contentious, with you, but why is it hard to pull off pairing a black and white glen plaid jacket with a light background with a blue shirt and charcoal pants? There's a good discussion of the joys of wearing light colored sc's on LL if you are curious.