That was my point, not because of the unfair balance, but because Fiery Souls wouldn't get it. However, once you update Elemental Savant, it will become more balanced. (Fiery Souls can completely pierce [Fire] creatures, while Icy Souls can pump their save DCs higher)While the effects of those two feats and nine levels are, indeed, a +5 to the DC... Is that really such a terrible thing? I'd say it was a ridiculous thing, myself, if it weren't for the fact that you had to blow two feats on it and are minimum level 14. Maybe my sense of balance is off today... I only feel bad that the Fiery Souls can't do the same thing.
Edit: By the way, you should remember that you're changing every [acid], [electricity], [fire] and [sonic] spell into a [cold] spell with the first level of the class, and upping the caps...so a +5 DC to the saving throw for all your damage spells...Just wanted you to be aware of that. Take from it what you will.