Well, I just I ordered a pair of SKS 451mm-specific fenders after some major hemming and hawing.
I love the look of the fenders and I expect them to be an excellent fit - both mechanically and visually - but these things are
only available from Tern, a company that's proved itself to have very little scruples. Their folding bikes crack in half and they spend their customer service time pointing fingers at consumers. In fact, I half expect some little Tern minion to come here and shame me for criticizing their company, as they've done in the Folding Bikes forum (and if they want to play it that way, I'm more than ready to don the brass knuckles for a digital fight of ethics).
At any rate, I
really regret handing them $43 of my money for these fenders, but at least they're an SKS product. If they do their job and look good, I'll be happy.
-Kurt