I've been trying my darnedest as of late to start reading sheet music and chord charts on a tablet. So far I can't find a tablet that has all the features I want.
-- 4:3 aspect ratio: 16:10 or 16:9 just suck for reading music. The extra width is nice in landscape mode, but the widescreen format is just a liability in portrait. As much as I wanted them to work, the more common widescreen formats just aren't going to get the job done.
-- something approaching a 12 inch screen: the iPad has the appropriate screen ratio, but it's still just a little small for comfort.
-- android or w7/w8: so far the iPad is the only device that comes close to meeting the previously mentioned criteria, but if you're not an apple person (I certainly am not), then that's kind of a drag.
-- active digitizer: it is sometimes necessary to add annotations to music. An active digitizer would certainly make that easier.
-- thin and light: the thinner and lighter the device, the less likely it is to fall off your music stand.
The best tablets for sheet music are almost here. The upcoming Toshiba Excite 13 is the largest tablet yet.
But my money's on the Lenovo Yoga 13, and if you're in the market for a new laptop I think that's the best way to go. It's a full sized, full powered, laptop/tablet hybrid that can do anything you want it to do and is (finally) big enough for sheet music.
Yeah the new convertibles are neat, but they possess a couple of undesirable aspects.
1) No active digitizer ( at least on the ones you suggested here)
2) Widescreen format is a terrible paper replacement. 4:3 is much better
3) Windows 8 - it's nice to have a full computer at your disposal, but most notation applications available for standard OSes (Finale, Sibelius) aren't designed with mobile use specifically in mind. Thus, their UIs and features are optimized for use on a standard screen with standard mouse/keyboard input.
I'm honestly more excited about the newest line of Jelly Bean Android tablets. I recently purchased a Samsung Galaxy Note II phone which features a great active digitizer. I'm looking forward to seeing this implemented on more tablets. If we can get one with a 4:3 aspect screen that is hopefully a bit larger than Apple's iPad, we're good to go!