Problem is, you just listed the 4 best talents in the game.
You shouldn't really think of Glass Cannon or Leech as a baseline for what talents should be. Both of them are ridiculously overpowered. Instead, think about Politician (-1 int, +2 charisma) or Far Out Man (+2 range on spells) or Zombie (heal from poison but die from normal healing).
90% of the existing talents are small buffs, or tradeoffs that specialize you.
I see talents as "feat" equivalents D&D wise. We don't necessarily have a standard for how powerful any one talent should be since they're so imbalanced right now. Some of the existing talents I feel are downgrades to a character even. Politician is a great example of that - it's a tradeoff but nigh-objecively a bad one considering the limited applications for a high charisma.
I personally think Far Out Man is quite strong though. But I have ended up playing almost exclusively mage and mage hybrid characters by now as I find everything else dull or reliant on the extremes of cheese(resistance stacking/stealth).
I don't mind if talents get toned down or up but I would like consistency. I don't like "no-brainer" talents that are just obviously your best choice for a build. I want an interesting personalized character build that provides enjoyable and balance gameplay, and I don't want to need to gimp my character to achieve that.
First, and this might seem a little off-topic, but Bully is a horrendously overrated talent from an efficiency perspective. Loosely translated, it reads "when you inflict negative status effects on your enemies, you win." You really don't need to spend a talent in order for this to be true; if your enemies are consistently Knocked Down, Slowed, or Crippled, you're going to win anyway. Bully seems much better than it is because it makes big, satisfying numbers pop up on the screen. Lightning Rod, for example, is much more efficient than Bully, because it's much more likely to decide the outcome of a battle. (The other three talents you listed, however, are powerful indeed.)
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But I do really care about what you, Fellgnome, think about Head Start, because from what I can tell you're the intended demographic for that kind of talent. With the others, there might be other people who might like them, but if you don't like Head Start, I can't imagine who would. Similar situation, but not quite as extreme, with Savour the Moment.
I disagree on bully. Midnight oil is cheap and can be used every turn. It doesn't take enemies completely out of the fight either, like stun or knockdown. It can be a very efficient talent. Also, stuns and knockdowns do have CDs, so it can be important to take down enemies before the effect runs out, depending on your party makeup.
Head Start as a talent doesn't really appeal to me. I'm trading a small gain for the first turn of combat in a game where I can often force the first turn to not matter at all. Recovery AP is much more important to me. With glass cannon, the gain to max AP does come into play more however, but only with glass cannon would this have any merit. Even then though, I'd probably pass on it for something more substantial feeling.