To the OP - I spent several years with Vortex and I asked these very questions...
What made me change - I had friends with swaro optics, and while I was debating whether or not something was a bush, they could tell me if it was a 5x5 or 6x6 bull at very long ranges. So that little extra quality does make a difference in that scenario. Regarding light-gathering, I will be honest I have compared a lot of bino's I struggle to tell any difference between alpha glass and other mid-range glass at dusk (just my eyes). but to that point, most alpha glass is truly better than mid grade bino's... but this is just like boots. Everyone is different, every model slightly different. So please don't take all these ideas as gospel. go find what works for you. Just google SLC vs EL's. you will find 100's of conflicting opinions on what is better.
For my eye's... I can't find a pair of binoculars more comfortable than my 10x42 EL's. I also have the newest SLC 15x56's.
And regarding the ranging bino's... you sacrifice the HD glass when you guy to the ranging bino's. (At least that used to be true, I know Swaro has made some updates. But El's have hd glass, the EL range bino's circa 2015 did not)