Hi,
When deciding what products to use, it's better to evaluate the products collectively within the context of what your goals are and what your lifestyle is. When others give their opinions on a product it's always based on how the product performs under their regime, which may or may not be similar to your own.
Sediment choice has to be evaluated in the following context:
1. Cost.
2. Appearance and feel.
3. Nutrient performance.
Item 1 is easy to assess, which it seems you have already thought about. If there are cheaper alternatives, which there are, then the value of the product is less in this sense.
Item 2 is subjective. Amazonia Aquasoil has an amazing velvety feel. If you will be rescaping constantly, or putting your hand in the sediment often, then there is value in a substrate that is not painful or irritating to work with. AS scores high in this department, but again there are other sediments that may be less irritating to work with.
Item 3 is arguably the most important item. As Ed mentions, the combination of nutrient performance of the sediment and the performance of the water column are cumulative. In Ed's case, he has fish which require a low water column TDS/Conductivity. He may therefore dose the water column lean to very lean, which put more emphasis on the substrate to perform. Others are forgetful or are out of town for extended periods and are therefore not able to dose the water column consistently. Having a nutritious substrate minimizes the penalties associated with these issues. In this sense both Amazonia and Columbo score high as they are among the richest of substrates. Again, there are cheaper ways to accomplish a nutritious substrate.
If neither of these factors apply to you (low TDS requirement and dosing schedule impediments) then the two products score low since there are much cheaper ways to add nutrition, water column being the most direct as well as being the cheapest.
If you take all three items into account collectively you can conclude that although both of these substrates are superior to something like sand, for example, Do you really need them to achieve success? The answer is no, unless some of the extenuating circumstances listed above apply to you.
Unless they apply to you then the substrate choice cannot make or break your tank as there are other factors which, if paid attention to will enable you to grow amazing plants even with an inferior substrate.
Cheers,