I sedate mine. There are 2 reasons horses don't like clipping 1) anxiety and fear 2) they've blown up before and gotten away with it so they keep doing it. All of our foals get clipped at some point before weaning and we do not sedate for those clip jobs unless we are going to a show and have to get legs and ears done correctly. The older horses are sedated as needed. At the first sign of resistance, we always start with a twitch (which releases endorphines that should relax the horse). If we are still unable to get the job finished, then we resort to sedation.
Now, a lot of people do not have a good understanding of sedation/anesthesia and how it works. Yes, there are risks involved with it. I happen to be a RVT with over 12 years experience in sedation and anesthesia so I am much more comfortable with it than the general lay person. Sedation allows the job to be completed successfully without anxiety, fear, and the physical fighting that ensues when a horse is scared. It relaxes the horse and allows the experience to be a pleasant one, which in turn, will allow the next clip job to be less stressful.
We've had horses here that would set back and try to bolt the second the clippers were turned on. But after an entire season of several clip jobs with sedation in the beginning, they progressed to standing still with a twitch for the legs and ears. The whole point of training is to teach a horse to accept an unnatural stimulus in a positive manner. If you are physically restraining/wrestling with them to get the job done, that is not positive. It just creates more anxiety, more fear, and bigger struggle the next time you need to clip them.
If you have only one or two horses and no place to be, you just want to be able to clip them then yes, you can slowly get them used to the clippers. But if you have plans to attend a rated show or you have more than 2 that need to be clipped well, sedation is the way to go.
I know I have a well adjusted horse when I clip them and DON'T have to call in the hubby to hold a twitch. He likes it that way too.