JR West presses on with adding fall preventers to various models, namely 221, 223, and 225 series. I'd be interested to know how long it will take to fit the whole fleet. My impression is that it's slow going, but I'm not sure.
227 and later subseries 521s have them from the factory, presumably 323 series will too. December 8 news item about 221 series: http://railf.jp/news/2015/12/10/170000.html December 4 news item about 225 series: http://railf.jp/news/2015/12/05/204500.html July 31 news item about 223-0 series: http://railf.jp/news/2015/08/01/205000.html July 9 news item about 223-6000 series: http://railf.jp/news/2015/07/11/210000.html
223-2000 at Shin-Osaka:
221 out of service on its way back to Kansai from Shimonoseki: