If so, can we expect the Samsung Ativ S running WP8 to last two days on its 2300 mAhr battery?
2 days in this age of Smart phone usage is truly the exception, not the rule. I want like 20 hours of time with no "Your battery is on life support, prepare to lose everything" message popping up. From that particular low bar, I am very happy with WP's performances. Both Titans 1 & 2 (which has LTE, though we do not live in an LTE area so I can not grade it's battery life) and my Focus S get well over a days use. I expect no less from the ATIV with a bigger battery.
Android has many advantages, battery life is not one of them. WP as a rule lives longer on a charge. In most devices, it isn't even close.
Eh, I've never had a device get over 15-16 hours on a single charge [Nokia Lumia 900]. So you think you're going to get 48 hours. Maybe is you put it in Airplane mode and let it sit and not use it. But other than that, you're being ridiculous.