You lost me a little bit on the frequencies - I think you're referring to the frequency of the METAR updates. I DO have an ADS-B reciever (SkyRadar L) and I can get the current METARS by panning the map in weather mode, tapping the airport symbol, memorizing the visibility and cloud cover, closing the box, panning the map, tapping the next airport along the route, and repeating. So in a minute or two depending on turbulence and pilot workload, I can have a mental picture of the clouds and visibilities ahead of me. Since this data is already available to the iFly via the SkyRadar (in flight) or WX update (flight planning), it would be nice to have it depicted on the vertical profile. Sure, the data may be old, just like the NEXRAD. The iFly notifies me when I'm outside of ADS-B coverage, so I would KNOW in that case that I'm no longer receiving updates. And since METARS are updated hourly unless there's a significent change, the depiction could expire after 60 minutes. Heck, if we really want to fancy it up we can also put a golden arrow at the most favorable altitude for the direction of flight, based on the forecast winds aloft.
An XM solution would hold no value to me personally, as my weatherwagon is hitched to ADS-B.
Thanks for listening!