Pretty happy with them - More durable than the AS-30 (the 30's last around half a game, while the 40's could last for 1 to 1.5 games in general). Also decent speed and flight consistency. Only detriment (well in the UK at least) is the price; but then again, the prices for feathers in the UK in general are darn high!
AS-40 does not exist in Japan, so I wouldn't know. But I would consider it to be a little less durable and "solid" than the 50, so I see it as a decent shuttle(good enough for tournaments). I usually used 2-3 F-70s though...