Ive sold RRR blocks for five figures...so those guys with that sort of coin would be interested.
personally unless your after over 1500hp a normal 05U block will do the job. Most of the big hp GTR's in this country are using 05U blocks without an issue. Blocks split and crack due to poor engine harmonics than anything else, an engine prepped and assembled properly with a sensible bore size will not have block issues. The only real advantage of the N1 item is the thicker deck which does in some applications prevent fatigue cracks around the head stud holes when running mega boost.