I have run the Wahoo BluSC for a couple of months, it is fairly reliable though the cadence sensor has wacked out a couple of times 42,000 rpm, I wish.
I do not like to ride with data in my face so the phone sits in my jersey while I ride, then I upload and check after.
I too have a battery pack, I have done 9 hours and still had over 50% phone power left.
Pirk