According to CDR-Zone.com, NEC's roadmap this year, include the shipment of a new recorder supporting DVD-RAM format, with up to 16X writing speed... Apart from the already known ND-3520A and the newly announced ND-3540A, the ND-4550, plans to offer even higher recording/re-writing speeds for almost all formats:

As you can notice, there would be another slim-line model, with the codename, ND-7550A, which also supports DVD-RAM format. Both Super Multi drives are not expected until the end of this year...