I hope, for the sake of HTC and all of you who are eager to get the Senseless One, that it is as good as the Sensified One. The HTC One with Sense is a pleasure to use, has no lag, and using the battery-saver mode (which I consistently with no performance issues for me) could last me two full days if needed. Additionally, the camera, SMS/MMS, phone, and browser apps are all better than stock (I own a NS4 and N7).
I am typing this on my HTC One. I constantly use the power saving feature (easily accessible from the notification menu) and have no performance issues at all. Snappy as can be and I get all the notifications that I want.
My phone has been off the charger for 14 hours. I have 73% left.