njkayaker

Using a Touring and 510 together that way seems odd to me.

The Touring doesn't do cadence or power. Outside of data that the Touring just doesn't measure, the data recording isn't any different.

If you already have the 510, it's there to be used but it doesn't make much sense to buy one for that purpose. (I actually run a cycle computer along with my 800, which lets me see other data when I am displaying the map data on the 800. I also don't have to charge the cycle computer.)

I have no idea how many people use the impromptu routing or how well it works (I'm a bit skeptical).

Smartphones are actually much more capable computers than the Garmins but the battery life is worse. They also tend to be harder to read in sunlight and are less weather-proof. You also it to work outside of cellular reception.

The available software is also limited (mostly because it's hard to make enough money for the effort required). That situation could be improving, though.