I’ve been tempted but have some of the same concerns listed here. One, it’s a big thing to drag around. Two, it is somewhat expensive if it doesn’t quite fit my processes. Three, as nice as writing on paper is, it isn’t searchable.
Tom Solid’s Digital Journal is an interesting thing to look at; it is a yearlong PDF journal that can be imported into various apps like GoodNotes. The 2019 version is now very cheap since the year is almost over so I bought it to take for a test run.
But, again, maybe too complicated? Maybe not quite the way my mind works?
So what I think I’m going to do for 2020 is make my own. It’s easy enough to design something in your word processor of choice, save to PDF and import into GoodNotes. And the nice thing about that is that if there’s something you want to add, change or delete you can just go ahead and do it.
Plus, you know, free.
(BTW, someone closely involved with this site shared some of his own on his website… 
)