Same problem with me also facing same issue and I also visited the service center and they also said that this phone is having no issues.
The stand by time is Far better on the Snapdragon version. I do get exactly same screen on time as you get with normal usage and with gaming it hardly last me 2hrs with full charge.
Please send an email to this: firstname.lastname@example.org
Next day they will call you and please explain your issue in detail. If many people keep complaining about the problem instead of getting adjusted Samsung will surely fix a fix and give a software update. If just one or two complain about this issue then no one cares.
Please do drop a mail to that regarding your issue.