CMOS/TTL chip questions (was: Cmos Latch Octal)

[Buck Buchanan]

At 03:31 AM 11/19/98 -0800, Arthur Harrison wrote:
>Regarding unequal intervals in clocked metal-gate CMOS devices
>such as the CD4017BE, CD4024BE, etc:
>Do not clock these devices form oscillators comprised of gates
>made of other CMOS "B" type devices, e.g., CD4001BE, CD4011BE,
>etc.
>Also, do not clock them from (generic number) 555 timers.
>Both these methods will result in erratic counts.
>A better clocking method is to use an oscillator made of "A" series parts,
>such as the CD4069UBE, CD4001AE, CD4011AE, etc, or, for high fixed

Hello,  Is there any chance you could explain why this is the case?  I'm
aware of some of the differences between A and B series CMOS and have heard
of conditons where A series is better... but it would seem like there must
be another way to go rather than use old parts.

Thanks much!

Buck