Do you have any information you can share about this? A few years ago, I could reliably use OpenVPN over UDP, as long as I switched ports out frequently. Some time ago (I don't remember when), this ceased to be the case, and I switched to PPTP and, more recently, Shadowsocks.
UDP used to work (~3 years ago) but currently it's blocked wholesale. OpenVPN over TCP gets throttled and blocked thanks to DPI too, an obfuscation layer is required because OpenVPN traffic is identifiable due to a fairly unique encryption fingerprint.
What has been your experience with UDP over GFW?