Patrick,
As an activator, I use APRS all the time when driving and hiking to summits and include the comment “En Route” in my beacons. When I reach the summit, I transmit a beacon that I am “In service” and use APRS2SOTA for spotting. While driving I have the -9 suffix on my callsign from my mobile radio and while hiking the -7 suffix from my HT. I carry my HT in the side pocket of my backpack so the antenna is exposed and higher up so often am able to hit digipeaters which will cause my track to come out on aprs.fi when I am on a trail. Many chasers have told me that they follow my APRS tracks to ascertain where I am and how close I am to reaching a summit. Because I invariably never make the ETA I post for my Alert on SOTAwatch, I figure the chasers who want to work me can know more accurately when I will arrive. When I am hiking down from a SOTA, I will change the comment in my HT to “Returning” so anyone who is following me can see that I am coming off the summit. I have activated SOTAs in 25 states and used APRS in all of them. In my Alert posts, I write that I will be using APRS.
Likewise as a chaser, I will look at the APRS tracks on aprs.fi of activators who are progressing toward a peak if they indicate in their Alert that they will be using APRS. For activators in Southern CA if I can receive their APRS beacon direct on my home QTH radio, I have been successful in sending them a text message via APRS and received texts back from them besides being able to tell how far they are away from me.
I also know if need be that my XYL KB6LAS can track my movements through APRS if I am late making it back for dinner!
Scott WA9STI WA6LE (club)
Los Angeles