I'm using the Acer W500. It's basically a notebook, but the "screen" actually contains the CPU/GPU and is detachable, so it becomes a tablet.

First thing I did was to replace Windows7 with Ubuntu and tweaked it to be touch friendly (using lots of inspiration from Maemo). I'd say it fits well with my N900, as both can use very much of the same programs, tools and scripts. After putting on a real OS I really like it now

That being said, If you're doing a lot of SSH-ing I'm not sure if the onscreen keyboard of tablets would cut it; I'd always take the W500's keyboard along (which doubles as a protector for the screen), but then it would basically be a notebook (~ 1kg).

If your priority is getting something light-weight and you can cope with an onscreen keyboard and a non-desktop non-open OS maybe it's worth waiting for the Samsung Galaxy Tab 7.7 - about half the weight of the iPad2, yet higher screen resolution.