Yet another post on the dice in Warhammer FRP 3rd Ed. I'm milking these plastic polyhedrons for all they're worth.
This time, the topic is the conservative and reckless stances. Here's a graph of very typical dice pool*. What the graphs show is the changes to the probability if the character is in a neutral stance, or if they are rolling 2 Conservative (green) dice or 2 Reckless (red) dice instead of 2 of the neutral Characteristics (blue) dice. The lines are even color-coded to make the charts easy to read.
Conservative (green) dice are always better than Characteristics (blue) dice.
Reckless (red) dice are better than Characteristics, as long as you don't have a really nasty bane result waiting in the wings. Before taking a reckless action, it's a good idea to look at the card and see what 1 bane would do to you. If you can't live with the result of 1 bane, you need to shift back towards neutral.
Red dice result in high variance, really extreme outcomes.
The charts show what happens out to 3 successes or boons. Most of the time, that's what's going to matter. However, there are some situations (first aid and recovery being the most common in the core rules) where you want lots of successes. When making those sorts of rolls, Reckless can really pay off. If we take extrapolate the numbers further out (to 4 to 6 successes) the red dice go further out and don't drop off as quickly.
There's an optional "Higher Lethality" rule in the GM's toolkit, where excess successes do more damage. If you use that optional rule, reckless looks much more appealing, since red dice will generate more high-success results.
These charts don't address Exertion or Delay icons. In general, those only matter at key moments and aren't the sort of thing that a chart like this can really account for. If one point of Stress or Fatigue will Strain you, or if two Recharge tokens or a change to Initiative order will derail your plans, then you're best off dropping back to neutral. The rest of the time, Green or Red is the way to go.
The best Reckless actions are one's whose cards achieve their results through the higher success lines, not the boons. A really nasty single-bane line can ruin an otherwise good reckless card.
The best conservative actions either have a good mix of boon and success results, or concentrate their power in a single success and don't need multiple successes to be worth it.
The following Talents turn Boons into Successes, and are thus best for a character who relies on Conservative Stance: Charismatic, Might Makes Right, Girding Oneself, Determined, Coordinated Efforts, Clever. A character who spends a lot of time in Reckless stance will rarely find it useful to activate them.
The following Talents generate additional Boons based on number of successes rolled, and thus are best for characters who rely on Reckless Stance: Silver Tongue, Deductive Reasoning. A character who spends a lot of time in Conservative stance will rarely get the full benefit out of them.
Since the green dice outperform the red across the two main axis of differentiation (i.e.: green roll slightly more successes, and far more boons) it seems likely that the designers intended for the impact of one Delay icon to be somewhat more potent than the impact of one Exertion icon. It's hard to say whether or not they achieved that goal. The fatigue or stress of Exertion is usually something you can afford to take a few times per encounter, where as your very first Delay can hose you pretty badly. However, building your character to minimize the impact of Delay requires fewer XP than building your character to cope with Exertion. The majority of the action cards have better results on the red side than the green, though, so perhaps the designers took that into account as well.
*: The dice pool in question would represent a character with 4 points of the relevant characteristic, 1 level of relevant skill and 1 bonus fortune die (from a specialization or talent, or from a situational modifier), rolling against 1 challenge die and 2 misfortune dice (either defense of the target, or a situational modifier). I ran a lot of other charts, but again this dice pool provides a good summary and representation of the main effects, plus it's likely to come in play quite often.