Maybe I am missing it... How can you tell which set of units is going to be used when joining a live match????

As far as I know, now it's impossible.

I created some matches and I don't se where you can select a different unit group? It looks like when creating battles for live competition, you have to use the MAN 2 standard units.

It's only for registered players to chance unit setup.

That is right, which means your opponent must be registered aswell.

Being registered(subscribed) is the only way to fly>>>(if the $$ is there, of course).....because of great selection of unit types, battle terrains that are also great....the trial maps are nowhere close to the subscriber maps...very nice diversion.