2gb file limit for extents depends wether enablelargefiles is on or not. you can just check for it by looking into the log files "Large database file access enabled for db" .
while doing a binary dump it should also write to multiple bd's.
Also note that if dumping data to a file through 4gl code 2 gb limit is in place wether or not enablelargefiles is set or not. so whenever dumping data to a file through 4gl always make sure to handle the size restriction.
Arshad