I didn't say length, I said body mass, which is far more important in regards to bio-load, which is one of the primary reasons that the inch of fish per gallon rule is ridiculous IMO. I've been keeping neon tetras for atleast a decade, I am very familiar with them, and the body mass of two (thickness) is absolutely more than 10 chili rasboras. That's why they are often referred to as mosquito rasbora, a name I personally prefer, because they are so tiny and skinny. To say there is a difference between 6 of them and 10 of them is silly IMO, and when you are talking about pretty much the smallest fish in the hobby, giving them a few more in their school so they feel comfortable is a good idea IME/O.
Corydoras pygmaeus are not bottom dwellers, they are mid tank shoalers, so I don't think they fill out the stock quite as nicely and/or may not be what the OP is looking for. They do not look or act like a typical cory, same for corydoras hastatus. Pygmaeus and hastatus are also much more difficult to have success with. Over the years I've had a harder time finding healthy specimens and have heard the same from many other hobbyists. I do keep a mixed group of pygmaeus and hastatus that I've had for atleast a couple years and I only ever see them at feeding time.
Corydoras pygmaeus are not bottom dwellers, they are mid tank shoalers, so I don't think they fill out the stock quite as nicely and/or may not be what the OP is looking for. They do not look or act like a typical cory, same for corydoras hastatus. Pygmaeus and hastatus are also much more difficult to have success with. Over the years I've had a harder time finding healthy specimens and have heard the same from many other hobbyists. I do keep a mixed group of pygmaeus and hastatus that I've had for atleast a couple years and I only ever see them at feeding time.