The Riteks, (though I hate to say so,) are very good being ricoh product. Also, Verbatim 4X RW's are very good in my NEC ND-3500 so far, and are highly recomended. As for the 4.38 Gigs being reported by InfoTool, you're going to get that with all "4.7 Gig" media. That's just the differance between the 1000 bits per kilobit that's TRUE, and the 1024 bytes per kilobit that is required in the PC world.
Now, as to the 2.4X writing speed, I'd check you drive's compatability chart agains the media type, adn see if perhaps your drives firmware may need to be updated to recognize this media as 4X.