The resin has a quality like the old lead glass... remember that stuff? It "falls"... i rented a business space in the downtown area of a small town that was nearing 100 years old... the glass in the windows "breathed"... the (original) glass had fallen to the base of the frame and was every bit of 3/8" thicker there than the top, and allowed air through the emerged opening at the top... the owner used some sort of gasket material he had to replace fairly often... to replace ithe glass or entire window was expensive and had to meet standards of the historical society people..
resin never truly solidifies... its like that glass... a knife across its face will heal over time as it "re pools". Its handy for these type applications, so long as it is face up amd doesn't cover a large expanse..
We're back to size, though... for areas that have an expanse of resin, I worry it will flow out of the corners and pop out at some point... wood contracts and expands and isnt near as stable as the resin (even though it is moving too)... so... i like using resin on areas where it won't expanse more than an inch or so. I like using insets for the larger area... that said, I've resined as much as a 10" circle 1"2" deep with no issues (except for coaxing the resin to dry clear and bubble free).
As far as inlays go, I generally use a carefully selected piece of wood for its grain... so it is already tougher than most examples even from the same larger piece. I like to cut them 1/2" thick so there is a LOT of "refinish" room for boards that see extreme use. The inlays are just like the rest of the board... theyll scar, but they wont look any worse for the wear even over years... and if they do? A few passes of increasing grit sandpaper and theyre good again.
I made a Texas longhorn clock for a buddy's smoke-pit/bar... the inlayed longhorn is maybe 1/4" thick at most (its pictured in the first post).. its likely more like .15 or so. Its fine and will be for that purpose... the board I made him, though, has a longhorn too- it looks a lot like the clock but the inlay on it is a full 1/2" thiick... and not only because it's a cutting board, but because that guy smokes a lot of ribs and brisket, and he straight up carves on the board. I gave him the board to do my research for me. I'll see if I cant find a picture of it...
Sapele, predominately, makes a dang hard thing to carve up.
So... Let's say that this is someone who will cut on the nice face of it. It'll be for my in-laws, who are older, and for a board of that size I'm not sure they'll be regularly flipping it over to cut on the back side instead of the front.
So the first thing is that my wife said we shouldn't go larger than 18x24.
But the second portion would be that if someone is cutting on the decorated face, is there a preference between using inlays, resin, etc? Is one more likely to hold up better under actual use?