It would be great to target specific sections of a route, ie. On Tempus Fugit km 12.1-19.2 or whatever the segment is. Whether or not .Erg mode is on could still be up to the user, but I think this makes a more dynamic and enjoyable workout experience. If I want to go do a “Hill Workout” I can hit the Hilly Route and look at all the distance markers from a previous route and program accordingly to make the workset on hills (instead of sometimes on a descent with massive wattage or a flat).
This could also be beneficial for training Time Trialists. If I have a regular TT workout I follow, and week 5 I complete the 10km interval on the same map faster than I did it on week 1, it’s a great metric to look forward to! Duration/FTP is great for general population, and not much is needed beyond it, but as you get more competitive athlete a Distance/FTP option would put a more valuable spin on it!