WSF & Unique are so close in performance, I would choose WSF if I wanted Unqiue w/ better metering. If you wanted one good metering powder for both calibers, that would be it, but it will not give you top performance in the 10mm. PP is good, but huge blast compared to WSF for only a slight performance gain IMO. If you want top 10mm loads, you want two powders IMO, one for the 40 & one just for the 10mm. If you want to run full pwoer loads for both, Longshot is my choice.
"Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified".