I was just cruising through the threads and saw someone had replied to this one and it reminded me that I'd started this post 14 months ago. Figured I'd post again about what I ended up doing.
Turns out I bought a really nice, used set of 12x50 ELs from the classifieds here last summer. I took those, my Meostar 15x56, and 10x42 SLCs and did some considerable testing with the AF resolution chart at end of the day, low light conditions, testing at 100 yards one evening and 200 yards the next. Again, I was after what lasted longest as light faded. The SLCs went out first. Then, it turned out that I could not discern any difference in image brightness between the ELs and the Meostars, right to dark. Yet because of the 3x more magnification, I the image was bigger (duh!) with the Meostars. So, given equivalent brightness (to MY eyes) and a bigger image (important when counting points and estimating inches), I was sold on the Meostars. Maybe 15x56 SLC would be better than the Meostars but I didn't have them (though my buddy does and he thinks my Meostars are right there with his SLCs).
I did then, however, use all 3 sets during deer season in November and December, testing them in hunting conditions, comparing in early morning and late evening. It confirmed that I liked the Meostars best. So, at some point in the near future I'll be posting for sale excellent condition 12x50 EL and 10x42 SLCs.
Again, everyone's eyes and needs are different; this is just what worked best for me.