Jake, the TopoFusion guys have the multiple users figured out. All they need is a link to a shared page from each unit. They have both an event page and a team page. The event page shows the course highlighted in red with baloons marking the start, finish and any other marks needed and the last position of each team. The team page shows which shows the course and the individual tracking for the individual team.
event page: http://www.topofusion.com/tracker-sail.php
team page: http://www.topofusion.com/tracker-saili.php?name=Craig%20Van%20Eaton
You get the team page by clicking on the name on the leaderboard. I screwed up my tracking at the beginning and when I picke up Bruce in Delray. I tried to send an "ok" and somehow turned off the tracking. Noticed it after a little while but you can see the holes in the route on my team page. Other than that I think it only missed one point. I had the unit on the mast.
I heard that the tracking is consistent at 10 minute intervals. If it misses one it sends the next 10 minutes. Also heard if you start the tracking at the same time (sync up) they will display pretty close to the same time. Will try to find that out this weekend.
If anyone is doing the MKL send me your shared page link and I can add you to the current event page.