The WSI system is a clear winner when it comes to its airmets and sigmets. The Bendix/King system doesn't present them at all, while the WSI offers both text and graphic depictions. I've always found it difficult to figure out the boundaries when I get them from HIWAS, but the MX20 displays the outline on the map. The color coding of the boundaries differentiates between convective, icing, surface turbulence, aloft turbulence, IFR, mountain obscuration and surface winds.
In the text display of TAFs for a given airport, the screen is divided to show the TAF at the top of the screen, and below that a table lists times and displays symbols to represent the current metar and the forecast for the prevailing conditions, temporary conditions and probable conditions.
Richard mentioned the resolution of the MX20 display, and it really is much nicer than that of the Bendix/King system. It's the sharp image that makes it possible for so much information to be displayed, although, admittedly, some of it's pretty small.
Getting Nexrad images into the cockpit, as Richard reported, has been a long time coming, but it's finally here and with a number of competitors offering their solutions. All the systems, whether uplink or downlink or broadcast or request/reply, have to gather the weather information, assemble the products and then deliver them to the cockpit. Because of the time it takes to gather the data, the systems are not being promoted as close-in storm-avoidance equipment. To borrow a military expression, they're strategic rather than tactical. Be that as it may, if you're religious about keeping 25 miles from thunderstorms, you probably won't get drenched or bounced around too much if you navigate wide alleyways between red blotches on the Nexrad map. In combination with a lightning detection device, the Nexrad images do for weather flying what GPS does for navigation. They let you know where you are and where weather things of interest are in relation to your position.
I flew home from our mano a mano much more familiar with the advantages and shortcomings of my WSI InFlight system. I was happy with my choice. The cost for the service is just under $50 per month, after installation of the receiver and antenna, which cost $4,995. (A pay-as-you-fly option at $19.95 per day plus $299 per year should be available soon.) That $50 per month is about what I pay for satellite television, and what's broadcast on the InFlight "channel" is much more interesting. The weather was clear for my flight home, but I exercised the InFlight system and entertained myself by watching the first major winter storm as it bullied its way toward the Northeast.