At moderate speeds, say 1-4MHz, when a BSF / BCF is in the
low microseconds, is there any advantage using gate ICs from
either the 74 or 4000 series ? For example 4081 vs 74xx08 or
4071 vs 74xx32. At what execution speed is it now wise to consider
moving from 4000 to 74. 4000 series seem to have stayed pretty
much the same over the years whilst the 74s are available in ever-
increasing speeds and lower voltages. Is there any greater functional
reliability/dependability by using 74HCMOS parts vs the 4000 original,
eg 74HC4040, at 5V and moderate clock speeds ?

Perhaps if someone has a brief history of the 74 generations from
the standard 7400 to the newer fast 3.3V ICs that would be interesting.

And two other questions --

Are Schmitt triggers always inverting ? More than once it would
have been nice to not use a pre-inverter gate on a 7414 or 4093

And what happened to the numbers between production ICs ? Looking
down a numerical listing of both types shows gaps.