hum.. I had 3 batteries for my previous Tytn II (because battery worn out, so if you want to keep same uptime 2 years after buying... need new battery). I have two on my n900. I use the spare from time to time. I had also two for my laptop (5h when buying, 10min after 3y.. classic).
I don't care if I need a screwdriver to change the battery, but it does feel less like a disposable device if I can change it.
But hey, if the battery last longer (on one charge and during the product life), then, well.

Also I have one msd for my media and one for meego DE
but if we can partition the device it's ok