It's fine. Extending Rage actually works in 3.5 as well, since their rage lasts 3+Con bonus (so for 14 Con + 4 Rage, about 7 rounds at low levels). So if a fight lasts longer than that, it will come in handy.
Changelog 17 May 2014
-Clarified Barbarian extend rage text
-Eldritch Blast progression tweaked for better damage at low-mid levels
-Truenamer: Lexicon Of Perfected Map reduced to 3 to remove Conjunctive Gate
-Lycanthrope: Added adaptation notes
-Machiavellian: added Boost Scathing Wit
-Combat Medic: added Boost Surgical Precision
-Xenoalchemist: Added Boost Harvest Material Skill
-Swarmlord added (Lix Lorn has given approval)