Hi,
I've done fairly extensive testing, and IPv6 support, while pretty solid on the carrier side, is still iffy on WiFi. Both iOS and Android have various reliability problems with IPv6 and WiFi, mostly related to acquiring a DNS address or maintaining a connection while roaming. Combine that with less-than-fully-baked IPv6 on some enterprise WiFi platforms, and it's easy to see that deploying WiFi IPv6 today is at least a challenge, and definitely a risk.
Android, for example, doesn't yet support DHCPv6 on WiFi (it's not needed on the carrier side, which does DNS intercept), and intermittently looses its unicast address on some hardware devices (notably tablets, in my experience). Even when android gets DHCPv6, or these hardware problems get solved, there will be several years of legacy devices in the field to contend with.
we had problems with IPv4 in the early days - people still adopted it. without adoption, the bugs/issues with clients dont get addressed. alan