Marr is one on my most desired units to have, she evades my grasp each time I roll for her.
Question would be as some have said above do you feel the need to have her in your main team. Aigis being a game that has maps that you build your team around can be hard to have a set team. I have one main team and females and males the rest are custom built teams for special tasks/maps. Not having Marr I couldn't say if she would be a addition to my main team although I would like her to be, her lack or range would be made up with her ability to heal 2 units at the same time which in some maps without poison is a godsend.
In place of her though I just use Iris and her heal bomb for tricky situations.