Is less than 24 bits worth it?

My first CD player, a Mission unit, had only 14 bit D/As, (oversampled) but was vastly superior to contemporary Sony units which boasted 16 bits, so I agree with sean (for a change). That being said, and all things being equal (which is not always true) 24 bits has potential for sonic improvement if the rest of the circuitry is up to it.

How does jitter have an effect? I don't know how CD players are commonly configured, but, if I were designing it the serial bits would be loaded into a buffer register in whatever irregular timing they might arrive with from the spinning disc. (Actually a set of buffer registers, for a cache of values). Then the 16 bit word would be output parallel to the D/A, and converted on a clock mark. Only the conversion clock mark needs to be timed accurately.