我的500A也是放在外接盒中直接更新韌體，沒問題。
根據這裡 的說法：
Firmware Upgrade 2.0H

Allows your Dual RW drive to record at 4X on 4X compatible DVD-/+R media.
Improves reading and writing performance and reliability.
Reduces vibration noise for the discs with unbalance or eccentricity.
Improves audio playback on written discs with stand alone systems.
Improves reading and writing performance with 8cm DVD-R/RW.


好像RW可以到4X，回家後再試試。