I got a strong Zigbee also and generally never have missed commands to all the lights I have. However, I have noticed some strange things with the blinds. Looking at the logs (I'm using the driver posted above). The attribute reporting is set to send a lot of messages as the blinds move so I think the Zigbee network is getting flooded. Since the hub is sending open/close to each blind as fast as the Zigbee transceiver will allow and as the blinds get the command they start transmitting their position once a couple start it overwhelms the network enough to cause some of the messages to get lost.
I need to play with the attribute reporting sometime.
