Sadly it has the opposite effect on my old spare 5s .. that drains 1% per hour on standby on 10.3 where it only drained 1% every 2 or 3 hours standby on 10.2. I hope it's better on Beta 2
I'd also consider the health of your battery into this. The device is a bit older and has probably gone through a lot of cycles. I'd say new software probably puts a higher strain on the battery right?