I use an iPhone mount on my bike not for answering calls and texting but for a speedometer app that I use. And now my gps talks. It works great with the Bluetooth. It's like turn in 300ft so instead of looking for the street sign I will be looking at the road plus
+1 on the bluetooth....
I was thinking about getting a mount, but decided to hold off. If I did, I think I would either try the Lifeproof mount (since I have a lifeproof case) or a Rammount.
If you don't mind spending the money, I recommend getting a bluetooth compatible communication system for you helmet.
I have an iPhone5 and a communication system for my helmet. I love it for long trips. I can enter the destination address in the iPhone before I leave, put the phone in my pocket, and then just listen to the directions. No need to ever take my eyes off the road.
Although probably not considered safe, I also listen to music... it's great because the cell phone will automatically reduce the music volume so you can hear the navigation directions.
I would recommend against the tank bag suggestion. I have a tank bag with the clear top to hold a map. Anytime I've had a map (old school paper one) or my cell phone / GPS on my tank bag, I've been tempted to look at it while riding... which is crazy dangerous. I think a bar mount would be a lot safer (although still dangerous).