Funny, I replaced the Atomic bridgepickup from my USA HSS standard by a VHII. I think quite some Fender pickups are decent sounding, like the Texas Specials and Nocasters. Even the stockpickups in a American Series telecaster were quite ok. I had the chance to play the Custom Shop Rory Gallagher strat, which has very fat sounding gritty pickups. I like really liked them.
I don't have that much experience with Gibson pickups. I like most of their P90's. In general people complain most about Burstbuckers (being shrill and uninspiring). You're right that the Mule is a copy of the 59 Gibson LP pickups. Mind you that the LP pickups from this era were quite bright. The current Gibson LP 59 reissues have custom wound buckers, but I have the idea they sound fatter and smoother than the originals.