I am the one that wrote the original kit comparison at TFP when I was MOD over there and I slanted it toward the TF-100 to help Dave get his new business off the ground when he first started TF Test kits(and it still appears in their Pool School essentially unchanged!). While the inclusion of the OTO kit with the TF-100 is nice it is not necessary(an can be had for under $10 from many mail order sources. You can find inexpensive OTO test kits for around $5 or so at places like Walmart and Ace Hardware. While not as nice as the taylor one they are serviceable. and the higher resolution pH test in the 2000 series kits (inclusing the K-2006 is a plus. Amato Industries usually has excellent prices on the K-2006 and on reagents, btw.