D
Anyway, here's a not-quite apples-to-apples comparison of 10K vs 100 ohm resistors in the output pull-downs. Before has quite a nasty ramp down. After has a little bit of ringing, but nothing that the system seems to be bothered by. Also, nothing worse than the before side ringing.
The other issue seems to be power delivery. Some of the older dupont wires I got from Amazon back in the day are, in a word, dog shit. They need to be replaced, but wiggling them and reseating them has fixed the issue for the time being.
Turns out that putting the 10K ohm resistors in place of the 1K ohm resistors in the clock and reset output buffers was the cause of the new clock circuit behaving worse than the old. I'd done that in the hopes that it would drive the outputs at about 0.1V higher, in the theory that voltage sag was the reason that things weren't working. However, with all of the stuff connected to the clock the 10K resulted in an unsatisfactory fall time. I ended up going completely in the opposite direction and putting 100s in place of the 10Ks to get a sharper falling clock edge at the expense of power usage. It seems to have paid off. I can now push the #MiniDragon to just over 15KHz whereas before it stopped operating at around 14KHz.