My bike is the old style as well, but the chain has 4 or 5mm of clearance when on the 36 cog. It's not much, but it's not rubbing. FWIW, I'm using a Shimano SLX long-cage derailleur. I replaced the Birdy chain hanger with a new one (one good thing about the Birdy is that it's very popular in Japan, and the better bike shops all have parts).
One interesting concern with the new 10 speed kit is the ground clearance. The lower pulley comes quite close to the ground, especially with the lower-profile Kojak tires.
BTW, for those who may be interested, Panasonic makes a tire in Japan specifically for the Birdy (or BD-1, as it is called here). The tire is called "Minit", or "Minits", it is a slick tire, and weighs 150 grams.
Last edited by Sangetsu; 03-02-11 at 09:43 AM.