2004 I bought a pair of 15x45 Zeiss Conquest binos. I had a speedgoat and mulie hunt coming up in WY that fall is partially the reason I bought them. I also knew I'd use them for long range deer hunting that I used to do on several properties back in those days. I still have them and they've been wonderful glasses, even taken them on vacation several times out west since. When summertime scouting long range and the 2-3 standsites I have that feature shots over 300yds, I still gladly use them. But I wouldn't want to use them for general, everyday deer hunting, especially in the woods! If most of your hunting is on fields, utility easements etc where views and shots are regularly over 300yds then you'll have purpose enough for that much magnification. If you think you'll be using them to "count points" at 40yds through heavy brush then I doubt you'll be satisfied. To "count points" with a 15x optic you'll want them mounted or at least have a windowsill/shooting rail to sit them on to steady them during use.
Even as good of quality glass as my Zeiss are they leave alot to be desired in low light conditions. To see well in dark conditions the human eye needs optics that deliver an exit pupil of at least 4mm. A 15x45 binocular only has an exit pupil of 3mm (45 divided by 5 = 3) and obviously the less quality the binocular the less clarity and image with that 3mm. For comparison a 10x40 has an exit pupil of 4mm, a 8x40= 5mm etc.... For a 15x bino to have a 4mm exit pupil the objective lenses will need to be at least 60mm (60 div 15 = 4). A 15x60 pair of binocs will be large, heavy and if they are any decent quality they will be VERY EXPEN$IVE!!!
I'd recommend you borrowing a pair of 12s and 15s from a bud and trying them first to see what they do for you before you spend the cash to find out you don't like them for several reasons!