I've been range testing, and the slower slugs seemed to group better in my USH 20. Lightfields were best and Buckhammers were pretty good. Of the faster slugs, Winchester Partition gold seems to group best. The grouping was decent, but not good enough for the slug to be any more useful than the slower slugs which grouped slightly better. IMO a fast, flat shooting slug has to group really well to be reliable for longer shots. Otherwise, what's the point? I didn't get the greatest groups with SST or Remington Accutip.
I am an inexperienced shooter, though, and I find myself questioning whether my fliers are the result of the slug-barrel fit or my own shooting errors. That is maddening, as the slugs are so expensive.
Right now, I think I am going to hunt with the Lightfields and order some Buckhammers to investigate further. Buckhammers have similar ballistics at less than half the cost. After hunting season, I'll probably retest Partition Gold as it shoots flatter than Lightfield or Buckhammer.