Sorry, R2/C1 (in your .png file).
Hi
Reconfigured R2/C1 so it produces a sharper rising edge.
Before doing so, I tried a simple simulation in an attempt to see which R/C config gave more reliable debounce results. (RCTest-CD4030B.png)
I tried a test by reconfiguring the FF in a standard manner, without the timing feedback circuit, and then simulated(RCTest-CD4030B-Std).
It began to produce unwanted output transitions. While interesting, I didn't think that mattered much since the debounce FF is configured as non-retriggerable anyway. So I chose Fig A.
I've been testing on a breadboard with 74HCT74 FF's, all seems to work.
I haven't had a chance to pick up a CD4013B yet..
Any suggestions welcome.