Stretch goals for skill specialists?

[Varyon]

Reliability: The 74% success rate (say) of the understudy may be enough for a mission to succeed, but the 98% success rate of the expert has a better chance of exceeding expectations. Say it's a mission to salvage valuable artifacts; the understudy manages to get most of them out intact, which is enough for the mission to count as a success, but the expert would get basically all of them out intact, making it a spectacular success.

Speed: For tasks where you can make multiple attempts, the expert will succeed sooner than the understudy (with 7 tasks that each take an hour per attempt, and assuming the same 74/98 split, the understudy will probably need 10 hours while the expert will likely get it done in 7). For tasks where this isn't the case, the understudy may need to Take Extra Time to reach an acceptable success rate, while the expert can simply work at normal speed - or even use Haste (if the understudy has effective skill 12 but an acceptable success rate is 90% they'll need to take 4x as long to get it to skill 14; meanwhile, if the expert has skill 16, they could use haste to get it done in 80% of the normal time at the same skill 14... meaning all told, the expert would complete the task in 1/5th the time of the understudy).

Degree: For tasks where Margin of Success matters, the expert will generally have a larger Margin. In the salvaging example, maybe the margin determines exactly how good of condition the items are extracted in (and thus how much the client is willing to pay). With skill 12 vs 16, the expert has a +4 to margin compared to the understudy, which may be significant. Note that, depending on how the skills are spread out, critical success rate can also be a factor here - that skill 16 expert is 5x more likely to get a critical success than that skill 12 understudy.