I think the logic goes as follows: 1.6 pounds is too heavy for holding it any significant amount of time. If computer requires some support for using it, then it does not really matter how much it weighs 1.6 or 2.3 or 5 pounds.
Considering I carry my iPad around quite a bit and use it while standing, it is much better to have 1.5 ( I have the wifi one) than 2.3 or in my case 5.5 pounds. Which is also why I don't get the it's too heavy comments, but I am probably used to it by now. It holds all the info for each of my projects and has made it so I am almost paperless. It is also why I got the iPad though.
In answer to the OP asking about using it as much as we thought or did at first....I use it for a lot more than I thought I would. Almost all the time unless drafting, editing video, or using Photoshop. But even then I still use it for reference. And I do most of my forum browsing and posting from it.
I find it very portable/mobile and have it with me most of the time. I have a mifi that I use with it and my laptop, so I only pay for one mobile internet service. Tom Bihn bag for when I only need the iPad, and can carry other stuff in it as well.
But I have also spent a some time getting it set up the way I want so it does what I need it to for work. As well as spending some money on apps that help make that possible. Which for me has made it an invaluable tool. For the OP it seems it is not the device for them. As I have said to my friends that ask about it...if you go to a lot of flash heavy sites the iPad isn't for you.
My only other suggestion for the OP is, if you are on the fence, write out what you want the device to do for you as well as how and where you want to use it. Then see if there is a way for the iPad to do all of that and if you truly can live without flash (seems from your post the answer to the last is no). Ask here about specific things you want to do with it and see what others have done. Then if you still feel it won't work for you sell it or give it away. Because in the back of my mind I think you don't want to admit it wasn't right for you, which if that is so..I can't blame you. It is a good chunk of money to get one, so you want it to be something that works for you. But if the 11" MBA is more suited to your needs, then by all means trade out for it. Get what works for you and your needs.
And yes I typed this on the iPad
