I don't know if that's the right way to look at it. My thought when I saw the 3.5 revision was: Finally, Resist Energy is worth prepping. OK, so everyone else here probably thinks that too. The point of it is that the balance issue is not only Resist Energy vs. Protection From energy; it is also Resist Energy vs. the other 2nd level spells and protection from energy vs. the other 3rd level spells.
I don't think there's a problem with resist vs. other 2nd level spells anymore. It's in the top tier--my 13th level cleric preps remove paralysis, spiritual weapon, healing lorecall, resist energy, and lesser restoration at that level. Any time the party wants more resist energy castings, it hurts to lose my other options. My 5th level cleric generally doesn't prep resist energy. It's a good spell, but there are other 2nd level spells he uses more often and there's just not room for it. My wizard characters, on the other hand, generally don't even know it. So, I think it's probably reasonably balanced: it's definitely a top tier second level spell, but not so powerful that everyone should prepare it at every level or that it dominates most characters' spell lists.
Protection from energy, on the other hand, is not one of the top shelf third level spells. An abjurer might learn it because it's one of the few 3rd level abjurations. A cleric with the protection domain will prep it and my clerics and mages would all prep it if we knew we were going up against a powerful mage who prefered a particular kind of energy--knocking 30 points off of an empowered delayed blast fireball just isn't that impressive. (However, energy immunity is a pretty good option for that situation as well and might be preferred).
So, I'd say the problem isn't that resist energy is too good. It seems about right for a 2nd level spell (judging by how I handle the opportunity costs). Protection from energy, on the other hand, is rather weak for a 3rd level spell. So the solution should be to beef up protection from energy. Removing the cap would make it more attractive at high levels. Making it 15 or 20hp/level would make it more attractive at lower levels. (Which is usually where it suffers vis a vis resist energy--at high levels, the opportunity cost of the 3rd level slot is lower since 3rd level spells are no longer viable top shelf offense and the likelihood of running into things like empowered cones of cold and maximized flame strikes is a lot higher). Making it 1 hour/level instead of 10 min/level would also make it a lot more attractive, but a lot of DMs probably wouldn't appreciate seeing it as an all day buff.
maggot said:
I've noticed this problem too: in 3.5 the second level spell (Resist) is better in all most all cases than the third level spell (Protection). In 3.0, Resist was a flat amount and lasted only 1min/level, while Protection had no cap, just 12hp/level. People rarely took Resist. With 3.5 they pumped up Resist in duration and effect, and limited Protection. Now people rarely take Protection.
My advice would be one of the following: limit Resist to 1min/level, don't scale resist, or don't cap Protection. Any one of those would restore the balance.