Well, no experience on alpha 10x50, since my Nikon 10x50 CF Action EX is not an alpha at all. But after buying it, I have been able to use it in many different environments and climates. I do hike a lot when I am birding (I prefer walking when many take their car). If you think weight could be a problem for you, take a lighter bin, but personally I don't have a problem with that. I also have been able to try some alphas (Leika and Swaro) other birders use, most of which are 8x something. Well, superb view, but my bino's view does not pale in comparison. On the other hand, I have been able to identify some species I would not have been able to see with just 8x. Field of view has been a problem only in some rare occasions (surprisingly, from home with birds on the trees in front of my windows!). I do enjoy the crepuscolar view which the big lenses make possible.
I think 10x50 could be the best "all around" birding bin (for my use), even if for some environments or situations an 8x30 (like the one I used to take with me) would be just fine. Some experienced birders would shun your bino, on the other hand one of the most able birders in my area uses the cheaper non waterproof Nikon Action model. But don't listen to so much advice (including mine), as there is a lot of subjectivity in this issue. Try for your own, and think for your own. What do you miss in your daily birding? In my case, it was that extra bit of magnification and the money to buy an expensive alpha, but that has to do with my birding style and with the country I am from (where flight distance is quite far away and wages low). Plus I was fond of the old Porro design. So my 10x50 works fine for me. Well, just decide on your own, this is my opinion.