Complex sentence: Gary endorses ESP Guitars as of September 2014 having for the longest time used guitars by Schecter Guitar Research and had a signature model through them, but previously used Ibanez, B.C. Rich and Jackson Guitars.
Split into simpler sentences: Gary endorses ESP Guitars as of September 2014 having for the longest time used guitars by Schecter Guitar Research and having had a signature model through them. He previously used Ibanez, B.C. Rich and Jackson Guitars.