To be honest I really can't see what the problem is. Converting you NEF filers to DNG, which is an open format by the way, is a fully automatic process and once started requires no further input from yourself.
As for it consuming more space I think you will find that the DNG version has a slightly smaller file size than the original NEF. So unless you keep both formats, and why would you as the DNG has all the information the NEF file had, you will actually save space.
Personally I convert all my files to DNG as a matter of course, even though I use CS5 which would happily open my D90 NEFs, and once I have checked to see the conversion went OK I delete the original NEFs. I only wish my D90 would save in DNG format natively, as does the Hasselblad, and if it's good enough for them it's good enough for me!
Hopefully one day all the camera manufactures will finally come to their senses and adopt a common format for their RAW files and we will see an end to this.
And as much as I hate to say it the good guys in all of this are Adobe who's DNG is still compatible with older versions of PS. The bad guys are the likes of Nikon who insist on changing their NEF format every time they launch a new model.
