Complex sentence: A number of drummers endorse or have endorsed Ayotte drums, including Jon Fishman (phish) Jeremy Taggart but most of those artists have gone on to endorse other companies willing to support them.
Split into simpler sentences: A number of drummers endorse or have endorsed Ayotte drums, including Jon Fishman of Phish and Jeremy Taggart. However, most of those artists have gone on to endorse other companies who were more willing and/or able to support them.