Update on sensors- I've been lazy and haven't mounted my spare phone yet, so just keeping my main Android phone running the Wahoo Fitness app with the RPM cadence sensor on my shoe and speed sensor on the front hub. I've only ridden on commutes since I've had the sensors, so it hasn't been a priority to get instantaneous readings.

Quick observations:

• The sensors are really easy to attach. I chose to use the shoe attachment because I switch between bikes, while I left the speed sensor strapped to my road bike because I can't go very fast on my other bike anyway. DC Rainmaker has an old post from 2014 where he noticed you can just slip the cadence sensor into your shoe or sock, and I confirmed that works fine on a stationary bike.
• While the sensors are easy to attach, Wahoo packs the bare minimum of instructions and their website is also not as informative as looking on YouTube for someone to actually explain how to attach their stuff.
• The app auto-syncs to Strava and the latest version has auto-pause. I also use the audio announcements feature to get a summary every mile of avg speed and cadence. It can do 1/2, 1, or 5 mile intervals, and also supports time-based announcements at 1, 5, or 10 minute intervals.
• The app UI is a bit strange since it seems to eschew the traditional app design. Having no experience with bike computers, I wonder if it's more similar to them? The primary buttons have no text so I had to figure out which menu/edit/dropdown to hit to get to what functionality. And the first time I used it, I didn't realize I could swipe through the display pages to see different information.
• Since the speed sensor data is useless when I keep my phone in my pocket, I've only really got any use out of the cadence readings so far. I've learned a lot about my preferred cadence, which is difficult to do low-tech because my commute has a lot of short sections with different grades, turns, and traffic conditions. Since the cadence readings show up on the Strava ride analysis, I've learned that I spin up faster for hills unless I'm out of the saddle (explaining my wife's dislike of hills as a stoker on our tandem), but am otherwise going at a steady respectable clip. Maybe once I get a phone mounted, I'll do some lower cadence training for fun.