It's hard to argue with the quality of Leica or Swarovski, given the choice all my glass would be Leica. Any time you increase power you lose brightness with any brand period... it has to do with what our eye can take in and process. Unfortunatley for us hunters that affects us the most when light is low (dusk and dawn). 8x is one of the best for low light no argument. for long range stuff if Leica made a 15x w/o a rangefinder thats what I would own but they dont ( a range finder in a bino you cant carry ariound you're neck to me is silly) , tried to buy a new Leica spotter year before last and was very difficult to find (impossible) ( so I didnt and bought a Swaro) if you want 15x binos (I dont know Vortex products) put your trust in Swaro's and you wont be sorry.
As far as strategies go I guess it just depends what works for you, personally I can sit behind a set of binos on a tripod all day (sit back and stretch, change focus, lock down, look through other bino's etc etc..) and not have problems with fatigue like spotters give me. It is my go to set up to find game and the spotter is what I use to evaluate what I have found. If I am going to sit and look an area over it with any signifcant distance out in front of me it will be with tripod mounted binos to start . Buy the best you can afford and you wont be disappointed with how much better you can see what is around you if you take the time to sit still and look around...
