Some comments on magnification by Stephen Ingraham :
: We have already noted, in the discussion above, two ways in which higher magnifications can adversely affect binocular handling performance. Higher magnifications generally limit both the field of view and the depth of field of binoculars. Worse, however, is magnification’s affect on image steadiness. As you increase the magnification, you are also magnifying every motion of the binoculars. It is next to impossible to extract information from an image that is bouncing around.
With practice, and given exceptionally well-balanced binoculars, the average birder can learn to extract detail from a 10 power image. Extracting detail from an 8 power image is even easier, and, in objective tests conducted by ZEISS, birders consistently extracted the most detail (at least on eye charts) from a 7 power image. As noted above, my experience has been that there is no practical difference in the amount of detail you can see in hand-held binoculars of equal quality between 7 and 10 power. There is, however, a real difference in the amount of fatigue generated over a day’s use.
The extra effort and concentration needed to hold 10x binoculars steady and extract detail will tire many birders after a fairly short time in the field, especially if the depth of field is shallow enough to require constant refocusing. A tired birder will, in the long run, see less. There are exceptions, of course, but my general recommendation, after years of testing and using binoculars, is that 8x is just about the ideal power for birding . . . enough power to give a satisfyingly large image of the bird, but not enough to cause undue fatigue. "
Taken from here : http://www.betterviewdesired.com/The...-Binocular.php
From your list the Vortex warranty really takes away the worry of the O rings wearing out on the little porro, and back with the Aculon Uttings have the A211 7x35 for £70.00.