We do MDA-MB-231 xenografts commercially (http://altogenlabs.com/xenograft-models/breast-cancer-xenograft/mda-mb-231-xenograft-model/) and they are generally successful. They do take over a month to run, but with starting matrigel injections the tumors are consistent and the growth curves are nice as well.
We have used MDA-MB-231s extensively and found them to be reliable. We have implanted them ID, SC and by intracardiac delivery for micrometastases development, and colleagues have implanted them orthotopically with great success. Also, with several clones available that express different reporter genes, you have lots of possibilities for non-invasive monitoring of tumour development.
We do MDA-MB-231 xenografts commercially (http://altogenlabs.com/xenograft-models/breast-cancer-xenograft/mda-mb-231-xenograft-model/) and they are generally successful. They do take over a month to run, but with starting matrigel injections the tumors are consistent and the growth curves are nice as well.