I love to get out and explore new areas on my bike, and I spend a lot of time studying the global heatmap and my personal heatmap searching for new places to ride. I also study other people's rides looking for ideas for my own routes. I would love to have the ability to see my personal heatmap projected onto someone else's ride to see if I have already passed through or close to the area they rode. I could save the other person's ride as a route and then see my heatmap in the route builder, but that adds an extra layer of complication. If the function already exists in the route builder, it should be pretty easy to add it as an option in the ride overview.