Without being specific, each of the tank programs I have encountered have shortcomings to various degrees. I know this because our clients have asked us to review output results that seem to be questionable. In a few cases it's simply a case that they input something incorrectly. Generally, it's a problem with not being updated or some type of programming glitch. No matter which one you select, always be wary of the results until you have established that all is working well. This may require some amount of checking by hand to be sure the outputs are correct.
Joe Tank