W8 tablet in May - a difficult choice

I'd like to buy a Windows tablet - if possible during the next 10 days or so. Originally, I sold my Surface RT to get the Pro instead, but unfortunately it's still not released and things have changed a little while I was waiting for it to arrive in the stores.

There are now some alternatives that are worth considering but all of them have certain drawbacks, so I'm having a very hard time to pick one. And on top of that, there's already rumors about another Surface model in June and then there's the Haswell CPU's which just makes me wonder if it would be a mistake to buy any W8 tablet right now.

The devices that I have been looking at the most (and in that order) are: Surface Pro, Lenovo ThinkPad Helix, ASUS Transformer Book TX300

What I need

What I need the device for the most are probably browsing the web, watching videos, gaming (x86 games like C&C Generals and Portal 2) and developing with Visual Studio and other tools of that kind. Note taking would also be nice but I've never tried it nor have I ever used a pressure-sensitive stylus, so that's more like a bonus feature. I'd probably never use it to draw anything though. On top of that, I also use RDP regularly and for some problem-solving cases it'd be awesome if I had 3G connectivity. A high-res screen and a fluid, lag-free experience is important to me because that's exactly the two things that I disliked about the Surface RT.

Surface Pro: probably the best build quality

Now, the Surface Pro does come with a digitizer (cool), but there's no 3G model available which is unfortunate and there's no way to extend the battery life like the others can do. Even though the Surface Pro by itself is a really nice tablet, it suddenly seems mediocre when compared to the other devices. It is, however, probably the cheapest of all three, even with the keyboard included in the price and it has an amazing build quality if it's anything like the Surface RT.

ThinkPad Helix: perhaps too many features?

The Lenovo Helix is just amazing spec-wise. It has pretty much any feature that I could imagine to include into a tablet PC. Core i7, 8GB RAM, 256GB SSD, digitizer, 3G, and the list goes on. The awesomeness comes with a high price tag though (2000 EUR!) and it makes me wonder if it's a bit overkill for my needs (why would I pay for NFC and another 4GB of RAM when I don't need that?). I also personally don't like the design that much. 3G, extended battery life and the sayings about how nice Lenovo's keyboards still make the Helix an attractive choice nonetheless.

ASUS TX300: why u no 3G?

Lastly, the ASUS Transformer Book TX300 caught my attention. I have to admit, at first I dismissed it as a cheap knock-off of the Helix, but it actually has some very unique features. Not only does it come with a backlit keyboard dock with another battery, but the dock also includes a 500GB HDD. This sounds like a good place to save x86 games that require a keyboard to play or to store large media files like movies. But then there's the drawbacks of course: this tablet has no 3G and does not support digitizers as the others do. Also, there have been reports of the dock donnection being somewhat loose and easy to break. The price of this one is pretty much in the middle of the Surface Pro and the Helix which makes sense, because that's just what the TX300 is.

The one I'm most interested in right now is probably the TX300 because it's available (sort of) and the price seems reasonable. But I am worried about the dock connection falling off the moment I thouch this thing and the overall build quality. I'm also unsure if 13.3" would harm the portability.

Does anyone have some first hand experiences with the Transformer Book or recommendations on which other device I should get?