AAI guide Michael Horst also made an attempt on August 5 (same day as Liam O'Sullivan's successful FKT), but with 5h15m he was unable to match O'Sullivan. On August 16 former Mount Everest speed record holder and AAI guide Lhakpa Gelu Sherpa attempted the Rainier record, but was hampered by a calf injury. He completed the climb in 5h39m43s.
Finally, on September 17, Mountain Madness guide Willie Benegas made the car-to-car trip in 4h40m59s, as reported here. Benegas took about 3h20m to reach the summit.
Benegas is quoted as saying:
"I didn't even know about the record when I went up [to Rainier]... It seems like everybody else is more excited about it than I am... I think somebody could reach the summit in three hours, easy. I think somebody can do [the round-trip climb] in four hours."