Yes, I upgraded from 64 GB to 512 GB. I also replaced the fan. I reinstalled SteamOS from USB I flashed with the steamOS recovery image. I used a USB C thumb drive, but I think a regular thumb drive would work if you have a dock with a USB port. It was very simple, I thought.
I won’t even consider buying until it’s been out for at least a year or two. By then the major bugs will have been fixed and all the content added.
Batman Arkham City, then I moved on to Arkham Knight but I streamed that from my desktop because it’s more demanding. Now I’m trying to figure out what to play next. Maybe Jedi Fallen Order.
I wish I hadn’t installed the update. I was hoping it would make the game run better on the steam deck, but it’s actually worse. I think they’ve increased the graphical fidelity, but it’s come at the expense of the battery. I found a work around to get the game launcher to come up so I could lower the graphics settings to improve battery life, but that doesn’t fix the bugs. They seem to have gotten worse with the update. Never change, Bethesda. Never change.