I've used all kinds of nitrate reducing schemes - all kinds - the pellets are my favourite by a mile. IMO, best bang for the buck.
Couple points to consider here, at least from what I can see:
The Aquamedic reactor is a more expensive approach hands down. With the pellets, 1/2 litre and a phosban reactor and you're set - probably about $100 startup cost.
Next, the concept of an anaerobic reactor isn't anything new. Heck, you can DIY yourself a pretty functional reactor using about 100m (or maybe 100', I dunno
) of 1/4" tubing to create a feed water devoid of oxygen and drip that over bioballs, exact same thing for probably about $30 worth of materials (just search on DIY nitrate reactor, you should find a bunch of projects).
The key differences though: if you crash your anaerobic bacteria culture, you crash your nitrate reduction and have to start over. The slightest air bubble will do that. Plus, you have to have an amazingly slow feed in order for the effluent to be nitrate free, so you can imagine that they are more of a "nitrate-free maintainer" rather than a "nitrate reducer and maintainer."
Last but not least, they won't do a thing for phosphate, whereas the pellets attack both nitrates and phosphates.
These pellets are full of win in my opinion.