Yes, you can click the " + " sign on the map and drill down to 200 ft with the device. The weather is a layer that is quickly turned on and off. You will see the weather at the 200' level.
According to XM and Garmin, the data rates and update times are listed in the GXM 40 manual. I cannot recall if the data age was provided for the weather on the Zumo 665LM
Only Baron Services
knows how fast they get the data from their sources and pass that on for satellite dissmenination via XM. I too am a private pilot and can say that they advised the weather data is the same information that is sent to GPS' that are certified on VFR and IFR flights. If its thorough and fast enough for that, it will handle a motorcycle ride.
If you were to switch to the Aera 510 for the upgraded Aviation weather packages available on those units, costs will be $1,249 for the device and approximately $150 for the motorcyle mounting hardware.
No, I am unaware of whether the Aera line will handle marine weather. Only the 8 digit code at time of purchase can tell that at this time. Will need the device and a GXM 40 antenna in hand. Finding that specific pre purchase answer is difficult at the moment (from either company). I am also unaware of if the unit will handle XM Navtraffic. However, as you move up to the Aera 550/560 they do handle Navteq FM Traffic with the optional GXM 20 antenna.
If this is a motorcycle unit, propose the Garmin Zumo 665LM. If this is an aviation unit, propsoe the Aera 550.
Cheyenne, WY. U.S.A.