I think the two networks have something to offer, however if they werent different, why would there be 2!? I think IVAO i great to learn how to fly online on even though their manuals arent very good, and then go onto more proffesional things such as VATSIM. Also the geographic issue, both networks seem to have their "Zones" on which there are always more pilots on one Network in that place.
Anyways, have you guys seen the ranking for the EURO2004 flight booking??? We're 2nd! A European VA above the Portuguese locals... shows me evreyday how EHM grows daily.
Cheers,
Alex;)