"Wolfgang" wrote
Tumbling in currents, artificals will do pretty much what naturals
do.....tumble.
LIVING naturals would tend to try and resist tumbling I'd think ( I would if
I were one ;-) and use their legs and such to fight for uprightedness
Interesting stuff to mess around with but, quite frankly, generally not
worth the trouble in terms of productivity.
I firmly believe that "having fun" is a major product of any hobby ( or good
job,ftm ) and nothing is as much fun as learning. Thus, "interesting
stuff" implies "fun" and "fun" infers "productive" when a major product is
having a good time ! I meet many people im my travels that seem to limit
the goal of fly fishing to the "fun of catching fish" .... there are many,
Many, MANY ways to increase the "productivity" of the sport beyond that
narrow view.
Not surprisingly, discussions of such techniques usually lead to
unpleasant exchanges about what constitutes "fly fishing." 
Crap, we started by talking about nymphing, so we're already beyond the
realm of 'real' fly fishing :-)
Oh, and, it IS possible to separate discuss from unpleasant ... honest g