There have been some good articles in Flying discussing the merits of these various systems. Yours is a good summary Tinstaafl.
In a recent article the aircraft had the lot - stormscope, weather radar, and composite data. It was interesting to read how close the weather radar and composite pictures were most of the time but equally the composite picture is not designed for slotting yourself into apparent gaps between cells.
It will be interesting to learn how old the data is in Europe and the exact area of cover. The systems also gives you real time TAFs and METARS, and you can even send texts from the aircraft via the Iridium network which is apparently the constellation used.
Interestingly the two main players in satellite communication do seem to be more inclinded to provide more competitve packages than has historically been the case. I keep a close eye on the kit used by long distance yachts. The days of sailors using SSB for internet connectivity are diminishing with some good data packages available at a reasonable price from the sat. providers.