I decided to cap Sprite off at 50 ranks and thought I did long ago. I was surprised when I bumped into her and she was telling me I had under 50 ranks. So, I stopped with Radium for a bit and started to train her again. I was told that 100 or even 200 ranks was good with her. Looks like I have a new goal.
Proximus is a healer trainer that teaches you how to get more range out of your healing. I would love to get a ledger out of him, but that means I need to train a lot with him. Right now I have over 300 ranks with him.
Another trainer I like to have a lot of ranks trained. This mammal works like Proximus, but she trains in group healing. Both Proximus and Radium effects the range of your healing aura allowing a healer to heal further away as long as you have the right equipment for it. I currently have over 50 ranks with her.
Horus is one of those healers you may want to train, because he helps with raising fallen exiles. This is important because you'll find exiles deeply injured that you'll need more training with him to get someone back on his or her feet. I'm currently at 150 ranks with him and planning to train a rank with him each time I see somebody I can almost heal from fallen.