I would onyl wear them if the horse needs a little extra encouragement. You said he was dead-sided, so yes I would consider using them. But seriously, use them properly. Don't be one of those idiots who tears up their horses sides because they jab the spurrs instead of rolling the spurs.
I've onyl had to use spurs on my Appendix mare, Annie. And boy, as soon as I did she was all "Yes, mom" and "Whatever you say, mom."
Did you know that every muscle is used when a horse moves? I need to be able to control every muscle. I use spurs as I don't like banging my horse on the sides when trying to manuever him. All it takes is a jingle of the spurs and were all good. Though my ex trainer beat my horse with his spurs(blood and all) it pissed me off. So I have to be careful not to use them harshly.
In my opinion you do not to be professionally trained to use spurs. My horse was trained with spurs and on his off days I use them. I ride with spurs that are rounded and way duller than a fork. There is no way my leg has enough power to drive it is his side to cause any discomfort. There is nothing wrong with spurs. Just be sure that if you use them you introduce them to your horse if he has never had any on him and barely touch him with them.