GuernseyMan
Mongoose
You said your group are expert at accounting or some such
Actuaries spend their working lives calculating probabilities for insurance companies and the like! I can hold my own at statistics, as an accounts lecturer, but I can't keep up with these guys. Dice probabilities for them is like adding up for the rest of us.
Just keep your eye on the Effect, which is all a Referee is really concerned with for skill checks. Nothing else.
Good point. I understand that a straight +1/+2 will add the effect but I can't imagine a situation where it would be easier to succeed but not easier to succeed well.
There are two points in which effect really matters:
Combat damage. If the shot is easier, for any reason, then it will probably inflict more damage. I think that's common sense. If you see more of a target you can hit a more vital spot. If the target is moving faster you can't place the attack so easily so the effect will be lower.
Skill chain. Not really a deal breaker if you get an additional +1 on the next roll because of a DM rather than boon/bane.
Other skills have various effects for effect! Again a quick scan through and I can't see any dealbreakers for an extra effect, especially as it maxes at +6.
The one surprise for me is that effect is not used for the timing of skills. Rather than "1D rounds to perform a task" I would expect to see "6 rounds minus the effect of the roll". Alternatively, to build up suspense allocate a "effect number" to a task and then make rolls each round until you succeed.
"It will take 20 effect points at a difficulty of 8+ to hack the door panel while your buddies cover you from the guards. Make a roll on your initiative each round and accumulate effect. Once you reach 20 the door opens. Obviously negative effect would be a setback and two failures in a row fails the whole attempt!"