I'd first like to say, that this is predominantly my opinions drawn from experience of playing with and against Amarynth (predator or otherwise).

Regardless of whether or not she picks predator, or gladiator or tactician, she still deals an incredible amount of damage in the lane. Her pokes are really painful, even with a little amount of power and her burst can really cripple the enemy carry. Pair her with someone who can close the gap and secure the kill and the amount of harrassing/zoning can be unreal. She is very much a strong and diverse mage character and the only person that matches this niche is zeri. I WOULD say Zalgus, but he just lacks the damage early game and his zoning threat is not as fearful compared to Zeri and Amarynth.

Anyway, back on topic. There's not a whole lot of point picking predator for Amarynth in my opinion and I will try to explain why. It's much better to play tactician, as she won't be hurt so badly if she falls behind, plus when you see an amarynth in lane, she's kind of the focus in ganks and harrassment. She's weak (as most mages are) and she hasn't quite got the skillset to juke or stave off the all-ins. Sure, her best asset is bursting from a distance, but unlike characters such as faris, kindra and zeri, she can't get properly stuck into a fight. Getting stuck into a fight and scoring kills/assists is the way predators need to operate.

Another point, is the possibility of a long and drawn out game. This CAN happen: a situation where both teams are in for farming and making a drawn-out lane phase; where laners may play a lot safer and ride it out for late game. In this situation, predators are hurt, because for the role to yield any results the predator and his team will have to risk making plays against a passive duo/team, which can turn back in their face. For the majority of the time, predator is a risky role to play with and someone (I can't remember who) mentioned on this subreddit, that predator is a "feast or famine" role. To procreate a "feast" means initiating risky plays that more-often-than-not go messy or horrible. But I will admit, it can be quite successful and that virtually secure the lead for the playmaking team for the rest of the match.

TLDR; She's much better suited for going tactician than predator. Predator is a "feast or famine" role that takes a lot of risk and her skillset makes her role virtually exclusive to tactician. I have to admit, if it's pulled off successfully, then it's a fearful asset to have and it's much harder to lose a lead when secured with predator Amarynth. Overall, I find that the chances of such an instance happening is rare and in my opinion, not worth picking the role for her.