I use them with hesitation. My 400's spend most of their time on track and only once have I had a set that needed chucking after 150 fast miles (300 in total) and to this day I can only assume they were a bad batch as normally get over 2000 fast group miles in before they move. The 300 mile ones looked like new, but just didnt want to work. have had 3000 plus on 090's.
They use thm on the CB500 cup and they are extremely fast out there.