Firmware updates to 7.2 on NowTV and other branded devices

Hi,

I'm developing a Channel and targeting firmware 7.2 as I was of the understanding Roku were rolling this out to all modern devices. 

But we have a NowTV device that is on 7.0 and no update currently available. Is it possible to get a list of the devices that support each firmware and the update schedule?

Thanks,

Ryan