Harrison have a book of Mohairs, some with a shot effect which is achieved by using two contrasting colours for the warp and weft. similar to a pick and pick. Where they differ is that a pick and pick is a twill weave which gives it the characteristic ladder effect, a shot mohair is typically a plain weave. Minnis also have a couple of shot mohairs at the back of their Fresco II book (0557, 0558). as well as plain mohairs.
I do not consider the original Tonik a summer cloth, to heavy in my opinion. I consider it more a dressy cloth for evening. Very crisp and sharp when tailored.