I would be interested in proof of your statement, I have seen a lot of people stating the same thing but can't find anything that supports this statement. The only thing I can think of, is that maybe the iPad doesn't have TRUE connective standby like the Surface does. I know my iPhone uses PUSH, which I would say is not TRUE active standby.
All other claims that the iPad has better battery life is just false as I have tested this myself. I was really impressed by my brothers iPad's battery life, as it only dropped 2% when I had played Plants VS Zombies for a few minutes. But then I noticed it dropped another 5% in a much shorter period of time, the iPad battery % gauge is really inconsistent and can't be relied upon.
Well, I have not counducted a formal research (obviously), but in my experience an iPad with wifi on loses about 1-2 % overnight, while my Surface 2 loses 5-7 %. Even my Windows phone drains battery % slower than Surface in similar circunstances, and the battery is far smaller and the hardware is a similiar architecture. Thus, something is wrong (not optimized) in the Windows 8/RT code.
All iOS devices can get messages, VoIP calls and other updates in real time while in Standby, so I don't know what is the difference with the ""real"" connected standby of Windows you mention.
Actually many times I wake up my Surface 2, and the new email or new message badges don't appear on the lock screen until 4 or 5 seconds later, like if it was updating after I woke it up. Also, apps like Bing News should be able to update the news in the background (something possible in iOS, I believe). Every time I open it I have to wait at least 10 seconds while it is gathering the latest news. So much for "real" Connected Standby.
And don't get me wrong, I like quite a lot Surface 2, as I can do things with it than an iPad can only dream of, but I am not stupid. Surface has its limitations and problems. Mainly software related ones. And I want it to get as many improvements as possible and to have fixed as many bugs as possible. Any Surface owner should wish the same.