I was able to retrieve my Customeffects Harmonic Percolator from the post office earlier today. The builder is based out of Poland, does quality work, and peddles his wares through Reverb.
Customeffects opted for a DC only variation on the original, no-frills vintage perc schem that crunches, blarts, and responds to playing dynamics as expected. It also has the characteristic slight HP hiss, which remains at a constant level regardless of the harmonics setting and will probably be a non-issue when using a real amp capable of generating feedback.
The Customeffects take on this circuit seems darker and smoother than the Fredric Effects Perky Harlot, but equally crisp with crunchier settings and able to maintain better definition at higher gain levels. The Zander Cafetiere is probably has more focused upper mids, while the JDM Little Steamer is more muted and compressed.
I now have 3 Harmonic Percolator variants on hand again and am eyeing at least 2 more. Much like the Big Muff, there's something magical about the circuit that compels me to collect multiple versions.