Today, David released a substantial update to Pedometer++ with an entirely new logic to coalesce steps registered by the iPhone and Apple Watch:
You might be wondering why I don’t use Apple’s Health.app merging system for this. After extensive testing about how that works I determined that it doesn’t really do a good job for step data. The Apple Health algorithm works around the concept of a ‘priority’ device. This priority device’s steps are then used in all instances except where that device is completely unavailable. In which case the secondary devices data is used to fill in the gaps.
The concept of a fixed priority device doesn’t really work for step data. As you move between the various activities of your daily life, the best device for measuring your movement is constantly switching. Thus you need a data merging algorithm that can dynamically analyze your step data and determine which device’s data is best at any particular time.
That is exactly what Pedometer++ now does. It goes through your daily data and can dynamically determine which device to use for any particular point in your day. The result is a much richer and complete picture of your daily activity than you’d get from Health.
I've tried many pedometer apps for iPhone and Apple Watch over the past few months, and I've noticed annoying discrepancies between data recorded by my iPhone and steps measured by Apple Watch. David's intelligent system to reconcile steps taken sounds like what I'm looking for. It's been a while since I wanted to really check out a new watchOS app, too.