GMDSS - Do you use the Group MMSI features?

My friend Tim Flanagan of Navagear recently posed this question on Panbo’s Marine Electronics forum:

I remain faithful to the idea that Group MMSI numbers OUGHT to allow vessel fleets, particularly recreational boaters, to communicate more easily. Yet I NEVER hear about them being used. What’s the deal?
It came up because of a comment I received on this Navagear item: MMSI Confusion: Group MMSI Numbers? I figured the reader probably wasn’t the only person with this type of question, so I posted a follow-up: MMSI Confusion: Group MMSI Numbers Redux.
The issues raised in both of those posts got me thinking, though: what’s the dang problem?! Partly, I suspect, the available user interfaces tend to discourage using DSC for anything other than distress hailing. On top of that, the coordination required among the “fleet” requires a bit more effort than most recreational (fishing, racing, cruising) fleets are probably willing to do. Are those two factors enough to effectively kill Group MMSI functionality? Or is there more to it?

Click HERE to see some of the responses (including my own), then let me know your thoughts on the effectiveness od Group MMSI and other advanced GMDSS features. Do you use them?