I bought the CRP-5 for the reason that I want to go onto commercial after PPL. You'll find that it being a slightly different computer makes no difference (and if someone does look a little wrong, it does come with a user manual that explanes how to use it quite well). It might also make things easier on the wind side as it is a much bigger computer than the CRP-1 - the slide rule side is the same as on the CRP-1 except that it has a few more features that are needed for ATPL but can be ignored for PPL. In short it's a very good computer and well worth it and really won't cause you any problems.