To answer the original question, 8x or 10x bino's are kinda a personal preferance. Some people can spot game a lot better with 8 power because it is easier to hold the 8x steady as compared to holding the 10x steady. Some people are better at holding bino's steady than others are and can get away with a higher power bino when hand held. I remember when I first got optics, I got a pair of 10x42's and a pair of 15x56's. My buddy was using an old beat up pair of Minox's on an Idaho muley hunt we were on. I let him use the 10x42's while I used the 15x56's thinking I had the advantage because I had the more powerful bino's. Well he easily out spotted me every time we stopped to glass and I couldn't figure it out. On the next hunt he had purchased his owne new pair of 10x42's and so I was using my 10x42's. Now I was spotting deer as easily as he was. The problem was that I could not hold the bino's steady enough to find deer while using the 15's but was not hampered as badly by the shake while using the 10's. You see, the more power you have the more you magnify the field of view. If you are shaking, the bigger power will just magnify the shake more. Later I learned to mount my bino's on a tripod.
I am a strong believer in a good spotter as well and I like nothing less than a 65mm objective. The picture with the mountain goat above is truley a good picture and shows how nice a pair of good bino's will show it at 3/4 of a mile with 8x bino's. But just imagine if you had a 20 power spotter. You could see the type of trees that are in the picture, see what the goat is eating. Now imagine if you had a 20x60 eyepiece. You could zoom in at 40 power and make out the black of his horns, hooves and eyes. Now if you zoom to 60 power, which is not always possible due to heat waves, light, etc., etc., you can see the magpie that is sitting on his back and judge his horns. With 8x bino's you can see the goat and you must hike closer to see if he is a shooter. With a spotter you can stay where you are and decide if he's a shooter or look at the other goat thats bedded in the tall grass 50 yards beyond the feeding goat or glass in another direction and find more goats. Many people save weight by using just a pair of bino's which is definitely critical on a backpack hunt. Some guys are very efficient with bino's and can hike multiple miles in a day. At 50 years old I'm finding it a little tougher to hike those long miles every day so I've learned to let my eyes do the walking. In the end it again boils down to personal preference and your style of hunting. Neither way is wrong, it is just what suits you best. fatrascal.