As to the instant-on, instant-off, maybe I'm just spoiled because I've got a Mac, but that's exactly what my laptop does right now, so I fail to see this as an issue. My laptop is only very, very rarely actually "off". It's almost always suspended and opening up the lid or closing it again is all the "power switch" I need.
I've had a number of different external keyboards for my Palm over the years and they just don't cut it. I invariably end up leaving it at home and either going with the laptop or the Palm by itself. Most of the keyboards were cute fold-up ones that weren't much bigger than the Palm itself so size wasn't an issue, but it was just too much of a hassle to set up somewhere I could use it, connect to the Palm (whether wireless or wired, there's usually still some connect process). The biggest downside is that with any of the foldable or flexible keyboards, you can't use your lap to type on. Think how often you pop open your laptop on your lap to type external PDA keyboards don't cut it.
That's basically where I ended up. That said, I sure wouldn't mind testing out a Foleo, but I think that in the end, I'd rather just keep the $500 for whenever the next /real/ Linux-based Palm PDA is finally released. Alternatively, I'll go with an openmoko phone. I had a Zaurus Linux-based PDA many years ago and it had as many features as any PDA I've seen since (battery life excluded).