As far as the E-mail I sent to Aviation consumer regarding their review of the 396, here is their response,
Sigh.
Move the magnet away from the compass and the effect goes away. I did notice it and should have mentioned it.
Personally, I don't think it's a showstopper for buying it, as long as you are aware of it. At the moment, there's no better way to get NEXRAD.
Garmin may be persuaded to remove the magnet. It's there because the antenna is an all-market device meant for use in boats and cars. Making an aviation specific version without the magnet is expensive and Garmin chose not to.
If it were me, I'd just move magnet away from the compass.
Accidents? I don't think so....
Paul Bertorelli
Editor
Aviation Consumer
This was their response to my inquiry, they don't seem to get it. If some sharp plaintiffs attorney gets wind of this it could cause major problems for Garmin. On top of all that, the warrantee is void if you remove the magnet, so goes any logic there. The magnet has nothing to do with the antennas ability to acquire XM signals. It only serves as an easy way to attach the antenna to a "dash board" of a boat or car.
The group purchase is available to anybody that is still interested, just PM me and I'll give you the specifics.