Yes I would. I've had shiatsu myself and on my horses. It really helped me when I suffering with some kind of fatigue thing after a virus and I get sessions for my horse as he really seems to enjoy it and having seen how good it made me feel I think it must be doing something for him too (he's now retired through injury so not using it for any kind of riding benefit)
I have tried it on both myself and the Ginger. Wasn't for me to be honest but the Ginger loves it, he does seem much better after treatment as well but to be honest I book it for the actual treatment.
For a horse that never really relaxes he turns into a dribbling mess who resorts to holding his head up by resting it on the door sausage or window ledge whilst being treated. I treat myself to an Osteopath and the Ginger gets his Shaitsu, seems fair to me
Also have a friend who's a qualified shiatsu practitioner. One of my ponies loved it and the other hated it. Bizarrely, it was the one who doesn't do cuddles or grooming that loved it, with the cuddly one hating it!