Eh, the 3 vs 4 buttons is more of an aesthetic preference for some people. 4 buttons makes your torso look longer, and I see it more in Dressage coats and in the jumper ring. 3 button coats are considered more traditional, and are more common in the hunter and equitation rings.

I actually really like the soft shell style coats, because the fabric is very breatheable! (Tho not quite as breathable as the mesh coats) Much better than the old-fashioned wool coats, now THAT was hot. And the shininess depends on the brand and the style. A lot of soft shell coats are no more shiny than traditional fabrics, while others have a little more glint to them, if you want to stand out ;)

I do eventing, and I like the 3-button show jackets better. The fabric for the soft shell is very breathable too.