Take a look on the Garmin website. It will tell you much of what you need to know about the G3X. You can also give a call to Garmin--most people find that their support staff are pretty helpful.

FWIW, Garmin often supports its products well after they stop making them. I have a 96C handheld GPS that they still support--I bought it a dozen years ago, and they stopped making them 10 years ago. My panel GPS is a 430W, installed about 5 years ago, and I think it's about the last one that they made--still supported "into the foreseeable future", according to them.

Another FWIW--there are 2 ways to keep Garmin devices up to date, either monthly on a subscription or just when you feel like it with one time updates. I use a subscription for my 430W, because I do fly IFR and want it to be as accurate as possible. I only do the 96C sporadically--went almost 2 years between the last update and one I did recently in July. The cost varies according to the product and the device being updated. All that info is on the Garmin website, also, but you'll have to search for it.

Cary