Technically I don't think that the GS shape (316 or 416) is "smaller" than a dreadnought, and if so only by a hair. The more pronounced waist will let it sit lower on your leg, so therefore yields a different feel when holding it....
Just to offer a technical point:
Taylor had published the total square inches of the soundboard in their past website. Yes, the GS
is a few sq.inches
smaller than their dred. But, that does
not make the tone "smaller" as there are
far too many factors of woods, top-b/s combinations, bracing, body shape, and varying build parameters that, in sum, make the GS and DN markedly different-sounding guitars. So no, I would not pick a guitar based on shape and size alone. But yes, the GS' narrower waist gives it a completely different feel playing seated compared to the DN's wider waist.
Edward