Would it be easier to RD Slinky Dog on a morning that does or doesn’t have EMH the week after Christmas? Regardless of which we choose, we will be leaving the park for brunch by 11 (then hopping to another park) so the crowds building later are not a concern.
I would do it on an a.m. EMH day if you can, rope dropping of course. The earlier the park opens, the fewer people who are willing to be there for rope drop. The difference may be marginal, but there’s a difference