I spent a lot of time looking at tablets to help with my IM work and I very quickly ruled out every iPad on the market for a few reasons-
1) Your locked down to 'apple approved' applications - and more often than not in the IM world you have to tweak things to get them to work how you want, not possible with Apple devices.
2) Looking at a purely hardware/technical specification point of view you don't get much for your money
3) To make full use of it, you would need an external keyboard of some type. Although iPad's do have some of the best keyboard addons I've seen they often cost $100-$150 on top of the already overpriced iPad.
4) Battery life was awful
In the end I settle for an Asus Transformer Pad which offered the best of both tablet and notebook worlds and the keyboard is actually a 16 hour battery as well.
Having played with my friends Surface recently I can also recommend that! Whatever you get, make sure it has a 10 inch screen, the smaller ones don't cut it