i don't know that it's "stronger" than clomid, but i do know of people that have successfully ovulated on letrazole when they've had no response to letrazole. i think it has a different hormonal action on the body and is possibly more gentle but works better. a lot of FS won't use it as yet as it due to it being used for breast cancer treatment, not for fertility issues - but i think there is a push for it to be moved across to being a standard treatment for anovulation cos they've seen good results.

if you have an FS that is prescribing it, jump at the chance to try it out

good luck!