More info :: 3790v SgMy(37xx with eCompass) can be 34xx too.
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I think there is no perfect firmware (even original from Garmin)., so it is good enough to try (if you need to know how about 34xx firmware on 37xx series) base on you can go back to original 37xx.

Who have a problem to get this alternative fw so you can PM to me then you have a chance to try it out by yourself ., you can flash back with original 37xx firmware to original 37xx if 34xx is not good for you .

You should have basic "How-To" about flashing firmware before. (if not., it's too dangerous.)
( I will not provide alternative firmware., just say "How-To" and you can get things from the internet for free.)