I use Eos for 4 mans and Selene for 8 mans and soloing. With Selene on sic she'll keep that sweet speed buff up, and usually will dispel any nasty debuffs about as fast as you can, so she's best left to her own devices. I find most of the time my heals are sufficient for any content and only use Eos for the party regen when I want to be lazy/dps more, or if I know the tank is pulling huge.