The original post is nearly a year old - I'm interested in knowing what the OP ultimately did (straight tracker or full capability?).
I have full capability with my TM-D710 and GreenLightLabs GPS710. (Well, I don't have a map display, as my automotive GPS isn't compatible with the trackers.) I have very rarely used the messaging feature, but I can definitely see a number of benefits:
- messaging between users just for 'fun' / casual use
- using the EMAIL-2 gateway, potentially having comms back to "the world" from outside cell range (I can be in places right now where I can't get a cell signal to send a text but can hit the local digi)
- and if you will please not mock me if I drag out the clichéd line about how it could be used as fall-back comms in a major emergency if cell/email/etc gets overloaded or fails.
I made a suggestion a year or so ago when I was first looking at APRS at how it could help the local ham group when we run car rally nets.. rather than spending time tying up the one repeater that's trying to run the actual rally, with timing & scoring info, send that across APRS messaging. There are some drawbacks and potential for points of failure in that concept, but it's another thing to think about.
One more thing you can do if you have messaging, which I've started playing with over the past couple months, is run (or use) a QRU server. QRU servers have a number of objects stored on them, but not overtly broadcast. Instead of beaconing them constantly and spamming the APRS frequency every 15 minutes with your coffee schedule etc., you can query the QRU server and ask it to give you x number of objects of type y nearest you.