alan....if you hadn't seen my post earlier this month, please do check out this link...you'll find the brand new New York Fahgettaboudit U-Lock which is the 'mini' you have been waiting for! It is scheduled to hit shelves at the beginning of the year.
Merton...it uses the same shackle thickness and crossbar thickness of the New York M18 that you've bought. It's still heavy, though, weighing in at 4.6 pounds.
It is going to carry the largest anti-theft protection offer in the world - $4,500 in the US

http://www.singletrackworld.com/article.php?sid=1722