If 2 MA's can't manage to interrupt a mage on a horse during his 5 minute cast time, then obviously that mage is overpowered. I agree. Yep.
Lesser heal is pretty fast, even on horse. I give you that. Perhaps, it could be a balance issue to be able to spam that on the own horse. I always thought horses are way too tank in MO1. I was hoping that would change.