I know about ACE. In dogs, probably okay. I would not allow it's use in any cat of mine. In fact I was very upset when my vet mentioned about a year ago, she thought we might have to give Mazy cat ACE for vet visits, because of her fear aggression. I quite calmly hit the roof a little and said that will never happen.
Not just because I adamantly feel that drugging cats, with ANY sedative, does not help them, it makes them even more fearful. But because dosage is not always accurate, and the wrong dose will kill a cat. I've read some pretty sad stories about it.