2008 ES 350 we logged 200,000 miles on 87 octane...no pinging. 2011 ES 350 we have 26,000 miles on it with 87 octane no pinging. Unless you get pre-ignition or pinging I would estimate that 87 is fine.
BTw, we also did 170,000 on the 2004 RX330 on 87 octane and 55,000 miles on a 2012 Avalon 2GR-Fe with 87 and no pinging.