8 hours ago, whafrog said:

A friend, as part of his PC's personality quirk, wanted to be a terrible driver who thought he was great. He also wanted to a be a great shot, because he was a cop, etc etc.

These are the sort of players you want as a GM. Too many times it's all about being the biggest and baddest. That gets boring after a while. When players understand it's more fun to have a unique character with personality, play becomes more fun for all involved.

I like to think about dice pools like this:

Adding a green die increases your "Capacity". Two green dice have the potential to roll up to 4 positive symbols. However, they tend to average just 1 positive symbol.

With a yellow die, you're capped at just 2 positive symbols, but most of the faces have 2 symbols on them, so you're using that "capacity" more efficiently.

So doing a rough average, 2 greens or 1 yellow are both probably going to roll 2-ish positive symbols. The 2 greens can potentially spike higher, making you more likely to succeed.