Good questions and should be easy enought to get you in the right direction.
A few items for you:
The Garmin Aera 510
, 550, 560 aviation/auto GPS units were all taken from the Garmin Zumo line. The physical device and many of the characterisitcs are direct lifts. You will find similar feature sets but the aviation units of course, will have pilot specific prompts and utilities as well as other upgrades.
XM provides the weather and it is all the same raw information. Baron
is the actual weather provider to XM. The different pricing tiers for the aviation weather are due to the amount of data that is sent rather than the accuracy.
There are two products lines. Navweather
is designed for newer cars and the Garmin Zumo 665LM. It provides big bold, easy to use weather data. The other is the Flight weather
. Flight Weather is designed for aviation.
The Garmin Zumo 665LM is currently designed to handle only the Navweather. There is an 8 digit code that can be enabled when calling XM and it is designed to be used with Navweather. The code is presented to XM and when they receive that code, their screen tells them what data package the device can handle. According to Garmin as of 1/4/2012, only Navweather can be processed and purchased.
Conversely, since the Aera line is designed for aviation, that device can handle the Navweather signals and includes the corresponding 8 digit code for Flight Weather as well. The Aera line also has a faster internal update rate and resolution.
For the aviation side, there is more data available to add on. The pricing tier and feature information is here
. There is no "higher" resolution or "better" information that you can buy either from XM or Garmin. What you are buying is "more" information from either the entry level Navweather to the sophsticated Flight Weather. XM provides all the weather information from these entry level units like the Aera and Zumo 665LM up to the big iron flight deck devices that go into jets. The larger, more expensive GPS panels use Doppler weather onboard the plane and supplement it with weather from XM and GPS positioning and other data from the Iridium satellite network.
The technical data you are looking for as to resolution rates, latency, is all listed in the Garmin GXM 40 antenna user manual. Here
is the link to the PDF. Page 33 will provide update times. The rest of the manual will go into details about what the antenna and data can do together.
We have used the Garmin Zumo 665LM with XM with Navweathere here and have found it to be a wondeful tool. There are no other competitors so your options are limited in either way. The weather data provides enough speed to let us know what to expect and where to reroute as needed. Suggest the Garmin Zumo 665LM, Navweather package for $9.95 and roll.
For general advice with your GPS, we suggest reading this
Cheyenne, WY. U.S.A.