A famous eventer/trainer of years gone by - Bruce Davidson? Tad Coffin? - recommended the braided rein/smooth rein combo for eventers under the logic that if you've slipped your reins or lost your reins over a big drop, it makes it easier to sort them out in a hurry. Good advice, and advice I've used. I showed a jumper and an eventer in that combo with a three ring snaffle.
However, the classic traditional hunter look is two *smooth* reins, one normal width, one skinny. But of course, I remember when hook stud reins were radical, and real hunter people had everything sewn in because it was a cleaner look.
Other than a Corinthian Class (I may be the only person left alive on the planet who remembers them) I don't think anyone cares.
What they do still care about is how the horse goes in the bit, how he moves and how he accepts contact. Don't worry about the rest.