If you are trying to choose between a horse or your unique mount, I would definitly stick with the unique mount, as there are many ways to reduce CA regen time dramatically. Now as for unique mount vs unmounted, I would strongly recommend unmounted if you have a bargainer or can just get high +run speed rings. If you cap out your run speed to 50%, which is ez to do with the right Leg armor set-piece and ring(s) than you will be running faster than if you were mounted on your unique mount (barring riding skill I would assume.) Unless you benefit strongly from a CA that is better (ie bigger radius or faster execution) while mounted then I would advise unmounted
Well, I understand your point but my main question I'm trying to figure out is that in the later levels does this unique mount +CA cast time eventually balance out with the -CA of my pyro spells? If so then being mounted would definatly be better, but as of right now the +CA is dramatically higher then the -CA time.