The _state_ of battery technology is the biggest issue _for_ inPulse. There's not much they can do, given the lack of viable battery technology available.
They _might_ be able to save a decent amount of battery life by using e-paper, but you lose color, and I'm not sure in practice you'd end up saving much power over the OLEDs they're currently using.
Seriously. When one has a 60x lead in lifetime over the other, you don't blame 'poor battery technology', especially when they use the same 'poor battery technology'!
Blame other interesting things you might want to wirelessly communicate with for standardizing on power-hungry Bluetooth rather than using a lower-power wireless tech (zigbee, ANT, etc) instead/additionally.
They _might_ be able to save a decent amount of battery life by using e-paper, but you lose color, and I'm not sure in practice you'd end up saving much power over the OLEDs they're currently using.