Retro fit bottom drain

Anyone have any experiences (good or bad) with the Tetra or any other
vacuum bottom drain?
Since I am going to do some replumbing anyway, I thought I might add a
bottom drain. However, putting in a true bottom drain seems a little
impractical right now as I would need to drain my pond to do it and
well, that would be a lot just to add that drain right now. Maybe in
the spring of 2006 just before I start things up again.
I am wondering if the vacuum bottom drain would be a better choice over
the submersible pump.
Thanks again, everybody!
W. Dale