Training horses always involves some risk of injury (or even death) to the horse, the trainer, any spectators, equipment used, etc. - this risk is totally your own as you will be making your own judgements on what to do. As with any suggestions on any subject you must weigh them out for yourself and proceed accordingly - at your own risk.
Often people have immense difficulty using electric clippers on one or more of their horses. What if you can actually reason with your horse and get it to willingly accept the clippers? Really - no fighting - no twitch - no sedation - just using an adaptation of the horse training principle called "pressure and release" to help them learn that the clippers will not eat them and the relax and cooperate response is the correct answer. Wouldn't that be better? I am including videos showing how I acclimated three different horses - each with a very different personality - to accept the electric clippers the very first time they ever had a pasture trim of their ears done.