I don't have one but I strongly considered one at one point. I went with a different DNA device instead. I don't think there is anything wrong with the gaia and I would expect it to be fairly durable as it's a metal body construction. I can't say for sure.
I do have a Smoant Cylon and I really like it a great deal. The handfeel is great, and it's just an all around great vape. .I've had mine a while, and I'm hard on my mods. It would be worth checking out, and well, see what you think of it.
If you are going for "as rugged as I can get" well the Geekvape Ages (designed to be shock proof, water proof, and for environments like construction sites) well, they have come out with at two battery version. It might be worth a look. You will pay a certain amount for that premium, but it may be worth it for you to do so, given you are searching for a durable mod. I don't think ANY mod is guaranteed to last a lifetime, but the Ages is pretty great when it comes to durability.
Good luck,
Anna