Honestly, even Eaters are relatively useless. Soul Charge and Eaters are nice "luxuries" and so so easy to get, therefore you might as well.
The difference they make in the grand scheme of things is really negligible' particularly on a mage. If you are looking to make a god like suit of course its nice, but it would not stop me playing at all.
The only time eaters are more than slightly useful are in pure mage duels without pots, which would immediately beg the question, why are you dueling pure mage with Eaters?
Soul charge may be beneficial on chars with mana issues? Never noticed it do much.
The difference between a great mage and a **** mage is the player, not soul charge.