OK, I've, by trial and error, figured at least part of it out. Both the hit Count and Conditional Breakpoints don't take effect for some reason unless another breakpoint is then added at some other location or is removed (the solid red dot turns to the red circle with a horizontal red line).
NOTE: seems to be fixed in V2.3.2
Same for disabling/reenabling a breakpoint (dot doesn't turn grey or back to red until another breakpoint is created/removed). Disable/enable All breakpoints works.
The Hit Count furthermore only works once - it is ignored after the first break even though the red circle/line remains in place.
The article I mentioned in my OP sez that the value of a variable will be displayed (with the debugger paused) by hovering over it in the sketch. That doesn't seem to work now - you get the usual popup containing the variable's characteristics but not the current value.
Conditional Breakpoints however do seem to persist but, again the change does not take place until another breakpoint is created or removed.
Also, don't do an upload while the debugger is running - it won't work and relaunch of the IDE is required.
Can sometimes recover proper operation after PC sleep by resetting the micro or replugging the USB port. Startup after hibernation OTOH seems to require a relaunch of the IDE.
As well, don't use more than 4 breakpoints at a time - it similarly won't work. No warning message is given if a 5th breakpoint is added.
Such fun...... 
And the irony - debugging the debugger.
Next up - Add Breakpoint works but Add Conditional Breakpoint or Logpoint commands have no effect. No apparent reason - had to relaunch IDE to recover.
Disable Breakpoint for Conditional Breakpoints, Hit Counts and Logpoints delete the breakpoint. Disable unconditional breakpoint works as expected.
Hit Count breakpoints only work for one cycle but are (all) reactivated when another breakpoint is added or removed.
Not related to breakpoints but the high contrast displays (both light and dark) don't show a difference in visibility between the vertical braces "connect" lines in focus and those not.
Just found that changing the value of a variable (while paused at a breakpoint) does not seem to take effect until a statement is executed after continue or step. Eg. put a breakpoint at an if(x==5) statement, change the value of x to 5, continue and the condition will not be met (assuming the value of x was not 5 to begin with). Therefore the break & change of x value has to be placed b/f the if statement.
Also, an annoyance, the "VARIABLES" part of the debug panel collapses, if expanded before, when continuing from a breakpoint.
PS: I note that these additions I have been making to this post bumps the post to the top and, since there have been no replies to this post (indicating lack of interest?), I hope this is not causing any annoyance to forum viewers. Please let me know if so....