"Effectiveness" is how good the results are of a method, "Efficiency" is how much result I can get, in comparison to the resources I need to spend (e.g. computing power for computational algorithms). I am searching for a word (ideally from of the same etymological origin, starting with "E"), that denotes the notion of "how far the range of application" is, in other words, in how many situations I can use this method.
"The algorithm is computationally expensive, so we need a powerful computer, but it is very effective, yielding great results and that (what is more) in a very a wide range of situations. Its WORD is its most impressive feature: We are will not have to implement any other algorithm."