Some thoughts on substrates

Hi All,
  I am fairly new to the area of planted tanks.  This means that I don't have
the experience that many of you have.  Sometimes this means that a lack of
preconceived notions may allow one to innovate.  It can also allow one to 
ramble on without understanding what they are talking about.  I don't know 
which category this post will fall into, but I wanted to get some feedback.
  It seems to me that Jim Kelly's method works for him because most of the
nutrients stay in the substrate.  The fine gravel (sand?) of the top layer
may isolate the substrate from the water to a large extent.  This allows 
feeding with stuff that would normally create an algae farm.  This differs
from the dupla setup that relies on circulation of the water through the 
substrate and feeding into the water.  Both rely on a high cec material to
 deliver nutrients to the roots.  Kelly's system attempts to feed the plants
 without putting the nutrients where the plants have to out-compete algae
for them.  The dupla regimen tries to put just the right stuff in the right
at the right time so that the plants use it all and algae doesn't get started
to well.
  Am I on base so far, or out in the ozone layer somewhere?
  OK, the problem with the Kelly method, if there is one, is that the
substrate may eventually need to be taken out and re-done.  The dupla method
because of the circulation through the substrate will not need this, at least
not as soon.
  Assuming that I haven't gone off on an expedition into la-la land with this
so far, I have a proposal to get the best of both worlds.  Kelly's system 
allows us to  treat the environment above and the substrate as two separate
environments.  Why not take advantage of this?  By setting up a small sump for
the substrate half of the environment and using a low flow pump of some sort
to move water out of the substrate and back in we could provide the best of 
both systems.  This could possibly be done with alternating output and input
tubes across the substrate.  If this would work we could feed the roots with
out having to allow algae to have access to the nutrients (the small sump 
could be in the dark).  We could then feed as heavily as the plants want and
with whatever nutrients they want.
  I plan on setting up a 10 gal. tank to test this unless someone convinces 
me that I am off base here.  Please feel free to comment on, pick apart, or 
add to these ideas.
       Sorry for the length of this post,