The ability to dial in some exposure compensation with auto-iso can be a major benefit in some situations but the more EV the more rapidly you shoot up the ISO
Not necessarily true Dave, a minus Ev comp will result in
lower ISO's. Dialing-in some Ev comp (be it + or -) is very often necessary for bird photography not matter what method you are using - it is still needed whether you use Av, Tv, or Manual mode with or without auto ISO. All you are trying to do is to correctly expose the bird and in this respect the ISO you will be using will be exactly the same given the same aperture and shutter speed. Using auto ISO does not change the amount of available light one iota.
With due respect Dave I do not think you are understanding what I am trying to say, maybe I am not explaining it very well. I will give the following example in an attempt to clarify things:-
Lets say you are shooting at 1/640 sec and f5.6 and you set an ISO of 400.
Now if you use 1/640 sec and f5.6 but this time you use auto ISO instead of setting it yourself you will find that the Camera will set an ISO of 400 and the exposures will be identical, it is impossible for the exposure to be any lighter or any darker as the camera is using the same metering system.
If you use manual mode (without Auto ISO) you are controlling the amount of Ev comp needed to correctly expose the bird by changing either the shutter speed,aperture or ISO - in this mode unless the metering gauge is at zero then you have applied some Ev comp.
I say once more that using auto ISO at a given aperture and shutter speed will result in precisely the same ISO as any other method and the exposure will also be identical. It cannot possible make the image brighter or darker.
BTW Dave when you use Manual mode how do you ensure the bird is correctly exposed, surely you do not just set things (ISO, shutter speed or aperture) so that the exposure meter is at zero do you?
Using manual mode without Ev Comp, if you want to use a certain shutter speed and aperture then the only way to control the exposure is to keep change the ISO.
When I use manual mode I control the exposure chiefly by changing the shutter speed - if the shutter speed drops below the minimum I require then I will have to change the ISO (manually), this method is fine if you are in a steady light situation but where the light is likely to change a lot (maybe a bird is going in and out of bushes) then it can be a pain - to this end using auto ISO is a real benefit BUT you need to be able to apply some Ev comp to correctly expose the bird.
Weather anyone uses Auto ISO or not is completely up to the individual and that's fair enough but to suggest that auto ISO can somehow change the exposure is completely wrong.
Anyway this stuff has deviated from the main thrust of the thread which is debating the up and coming 7D2 so I will leave it there on this one.