I have a tm2, it's very nice.
I have a tm2. I don't play games on it and it is a lot heavier than an ipad but it is running Windows 7 and office 2010 (including Visio) without any trouble.
I don't know about the Slate but when I use the tm2 stylus the digitizer is active and the touchscreen is ignored - I rest my hand on the screen all the time to mark up word docs or do some drawing. If I don't use the stylus then it uses the multitouch touchscreen.
I chose it over the iPad as it came with 320gb of storage, a grown up operating system and the ability to create as well as consume - it's a real copmuter not a shiny toy. And In case anybody thinks I am anti (or pro) Apple (or Microsoft) I also have an iPhone 4, iMac, MacBook and another Windows 7 desktop replacement machine. It's about the best solution to various requirements, there all good at what they're for. The iPad just doesn't do anything that the tm2 or iPhone (or a netbook) doesn't do as well or better for less.