What you say makes perfect sense to me...especially the bit about power management.
I was expecting things to happen like this:
Henrycat's device had no power management onboard, it lasted for about 4 hours. WiFi was on all the time, Wacom was on, Processor running full-speed and lots of unoptimized code.
Now, Power.management is enabled and the battery-life goes to about 20 hours (everything is off or low-power as long as you don't refresh the screen, connect to network or write with the stylus).
Then it's time for the baby-steps we're seeing now, little tweaking here and there giving us slightly improved battery-life.
End of Story.
I've complained about this at the iRex forums a while ago, and was told that it is a difficult process, that some drivers don't like low-power mode and stuff like that. That made me seriously doubtful...and the announcement of 5-10% increase for 2.7 that was over a month of dev. work and will still be a good 2 weeks "under construction" sounds more like "cleaning code" than like serious base-level Power-management work.