lots of places i fly have marginal reception while low, and sometimes the celings are such that you end up staying low. New years day i couldnt get any radar returns on ADS B coming through southwest montana. It was getting dark. Destination was home at Coeur D alene, Idaho. About 25 miles out of missoula it started to snow. ADS-B shows nothing. i change destination to missoula, and am finally able to pick up flight following 10 miles out of missoula, and am told of an area of moderate precip between me and missoula. ADS B finally loaded as i got into the missoula valley. Another place i fly, i cant get cell coverage on the ground. SO, i made the decision to get XM on my new avionics. Once i power the avionics, i can spend a few mins on the ground reviewing the WX for the return trip home and confirming it looks like what i thought it should. The GDL52r pushed the info to both the G3x units and my ipad. personally, i like XM weather and radio in the cockpit, but ADS B does do some thing better, such as turbulence layers.
Bryan