I went through this debate a while back. I was looking at the exact Wahoo Fitness sensor you are. I went with a Garmin Edge 500. I just found that no matter how I sliced it, the iPhone w/ Wahoo setup would be a kluge. There would have to be a weather sealing solution, mounting solution, battery solution (I too was riding about an hour during the week and 2 on the weekend. That changed. Rode 4 yesterday.), etc. Plus once all that was taken care of, I would have an LCD screen that was difficult to see in bright sun, and I would be using data, which can be a concern. It became clear that a purpose-built device would be best. The Edge 500 takes care of all of the issues of the phone without giving up necessary functionality. You do lose some frills (maps, other apps), but those would be distractions for me that I do not need.
As for apps, is there not cycling app from Android that will accept the Wahoo sensor data? I find that hard to believe. I am sure there are several that would accept ANT+, so I would imagine they would accept the Bluetooth as well.