Custom spreadsheet solutions which survive long after the developer has "left the scene", are often those which users accept because they discover it _ among other benefits _ makes their work quicker and easier to do. That is why the best person to develop such solutions tend to be one who works in that area, and is therefore familiar with the way the manual system operates. S/he would have an "insider's" perspective of the best way to introduce automation other users will readily adopt _ even as it solves the identified problem(s).
I believe using either of these two applications should not pose any problems for implementing your spreadsheet automation ideas. This is because both have always been "friendly", towards making it easy for users to get more functionality out of them by way of custom programming.
The 80ᚼ Pareto principle is based on Pareto's theory that 80% of the results one gets in a particular endeavour will be mainly due to 20% of areas to which one has applied efforts. In business this principle has been found to be true. Your data, properly converted into appropriate performance indicators, will show you where your largest margins come from. You can then channel more time and effort in that direction.
A person with proven competence in this area CAN become "notorious" for developing spreadsheet applications, which eliminate drudgery from the process of using MS Excel to handle large amounts of data. Typically, work that takes hours or days will suddenly take minutes or seconds to finish.
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