I've used the 139gr and 136gr L on pronghorn and deer out of a 260 Rem. I can't tell a difference in on game performance or on a target. Nothing but good things to say about each. I'll likely not use a different bullet out of that rifle.
My current WT Creed load is with 136L Scenars. I was wondering what difference you saw with them vs. the 139, which I also like. You noted not much difference regarding terminal performance. My Creed shoots sub half MOA with the 123 Scenar. I went with a slightly heavier bullet for WT's, just never killed one. Too many other projects. Maybe I should stick with the 123's.