Hi Jay,
Here are my experiences with the XM for my EKP-IV.
I was one of the first people to have this equipment. I actually flew up to Hyanis Mass. to meet with the factory rep to run me through the setup and operation. This was several days after the release announcement
I met with Dan from AVMAp, who had brought along my new WxWorx receiver, along with his own receiver. As my receiver was not activated through XM, which can take several hours, he set up his receiver with my EKP -IV The setup was straight forward requiring only a second antenna and a plug in cable from the WxWorx receiver to the EKP unit, plus a 12 volt power source for the WxWorx receiver
The unit booted up, which takes about 10 minutes to activate all the functions.
Dan showed me the various menu's and screens, which were easy to learn, and I was on my way.
On my return trip to FRG, which was about 1 hour, the XM function would not activate. I assumed this was because the XM subscription had not been put in place, which did not alarm me.
I arrived home, and removed the entire system, EKP, WxWorx receiver, and antennas and power cords, plus a battery pack and brought them home with me.
I set the unit up at home, and by the next morning, I was only able to receive METAR's . The unit should have been able to receive TAF's and NEXRAD radar.
After numerous phone calls to WxWorx (useless) XM- (Almost useless) and AvMAp ( Helpful) , and much finger pointing, the problem was finally diagnosed as a software "glitch" in the AvMap system. This was readily rectified by downloading additional software from AvMAp's web site. This software upgrade required me to purchase a card reader from Radio Shack for $20.00 ( a good idea anyway because database upgrades can now be accomplished online)
I have now installed the unit on my Cessna 310, which required a lot of creative cable management. (I have no idea why AvMap gives you 30 feet of antenna cable and WxWorx gives you 20 feet!)
The unit seems to work fine in flight.
I signed up for the least expensive service, which was $30.00 per month. The only thing the more expensive service would give me is cloud to ground lightening, and as I have a stormscope, was of little value to me.
I now have NEXRAD, TAF, Metar and color differentiation of different types and intensities of precip. AvMap tells me that TFRs will become available later in the year, and be available as a download at no additional charge.
TFRs are also included in the least expensive XM package.
Finding TAFs at other airports other than your home airport is a bit cumbersome, but is doable.
All in all, a well spent $600.00. This makes a great unit even better! Now we can start agitation for traffic on the EKP-IV
Hope this helps you.
Steve