Thiss is a huge jump when you get to level 21. Obviously it would be hard to do otherwise in character builder (you could give all of Great Fortitude/Lightning Reflexes/Iron Will free at level 15, and then give choice of Epic X feat at level 21, which would space it out a bit), but at the moment there's a huge gap between Paragon and Epic levels.
Part of the idea of these solutions seems to be that you'll use them instead of the Epic FRW (and Robust/Paragon Defenses) feats from PHII, which seem like inappropriate ways of trying to solve the underlying math problem. The way you've done it Great Fortitude/Lightning Reflexes/Iron Will are essentially obsolete, and the only save boosting feats that will get taken are the Epic FRW bunch. Not to mention other random and probably undesirable effects; for example, Shield Specialization is reduced to giving +1 AC under this change, because its feat bonus doesn't stack with the bonus feat you already have.
