Generic d20 class design?

[fireinthedust]

so I'm working on a modern setting with vampires and mages and cyborgs. They're detectives. The catch is that I'm using d20 material as the rules set, including d20 future cybernetics. Also the Monte Cook World of Darkness rules for the vampires and mages, as tweaked by me.

The non-vampires/mages are this Generic class that I'm working on. Basically I want it to be like the Talent Tree classes from d20 Modern and SWSE, where every other level the PC gets a talent.

Question: Are there serious pitfalls to talent trees that I should be aware of?

basically the PC doesn't have any empty levels, and I've left many of the feats open.

Houserules to be aware of: I'm changing all saving throws to static defenses that the monster attacks, or the spell attacks the static defence of the PC. This means it's more like SWSE, and I like that.

I'm also changing things so everyone uses d20+1/2 level+stat for most rolls, as I already don't like BAB from original 3.x

The main thing I'm worried about is that the generic character's player is a massive power gamer with a long history of breaking systems and making DMs cry.

example

Dwarven defender on a flying carpet, so he could do his stance and move around at the same time. RAW, he told me, he could do this.
Not as bad as the player who made an extending spiked chain and great cleaved through my army of minotaurs, but you get what I'm saying.

[ValhallaGH]

You are the Game Master. The game is run by you, it is not run by the rules. Your word is law, and if they don't like it then they can either learn to deal or leave the game.
Oh, and your munchkin isn't as clever as he thinks he is:

Spoiler:

Originally Posted by defensive stance

While in a defensive stance, a defender cannot use skills or abilities that would require him to shift his position.

Using a flying carpet to move certainly counts as using an ability that would require him to shift his position; especially since such judgments are made by the DM.

There are few to no serious pitfalls to talent trees, per se. The presence or absence of actual pitfalls depends entirely upon the talents available, and how they combine with other talents, feats, skills, powers and items.

Good luck.

[Mustrum_Ridcully]

A pitfall is: Don't make the talents boring.

d20 Modern is already an offender on this. "Melee Smash". Gives you +1 to damage. Really interesting... Not. Especially since you can get it basically three times.
Don't make them too fiddly either. I think Tough Hero has an ability that gives you back your Constitution modifier in hit points. A very small benefit for picking a talent slot and having to take some kind fo action during combat.

I think you should look more into Starwars Saga Edition or D&D 4 (powers and class features.) to create your talents.

Talents should make your character do something defining for him that's also worthy to have. A +1 to damage is not really defining.
A +1d6 to damage if you flank someone is a lot more noteworthy. It creates a context for the talent - you have to do something to get a benefit, the benefit is noteworthy, and the character plays differently from one without the talent. But adding another 1d6 doesn't really make things interesting, so it should either happen automatically or not at all.