My size, somewhat nearby, and rare enough to make me think about it. However I already have a Super Leggera from the same year, and I doubt this would ride very differently. The first photo in the CL ad also makes me wonder if there might be a bent fork. I decided to pass, but still think it's an intriguing model.
Here is a site from a different owner that has an original advertisement with interesting background information on the X4:
http://members.jcom.home.ne.jp/my_bianchi/algentin.htm