Designing a wing for competition is of course different than for normal, everyday use. First, you must identify what sort of competition you're looking to partake in. If you're looking to compete on a closed course such as in pylon racing, that would pose a different set of design requirements than a straight, cross country application. In a pylon race you're typically spending a substantial percentage of the flight in a turn so there you're optimizing for a higher G load than when optimizing for level cruise. As such, let's look at some guidelines:
1) In any competition it's the little things that will add up to penalties. One of these is the wing's moment coefficient and thus the plane's trim drag. In picking the section you really want to minimize the moment - remember that the sections such as those of the NLF family were designed for much higher wing loading that what we see in GA so the accompanying moment they represent would not be good for application here. Realistically you'd like to keep the moment coefficient somewhere in the -.05 range, with some variation accounting for differences in the camber line. The aft loaded sections such as the NLF(1)-0215 will be characterized by fairly high moment coefficients, which in my opinion would take them out of the running fairly early on in the selection process. For instance, the -0215 section is characterized by a cm.ac of -.15 in the range of cruise lift coefficient values. It is interesting that the higher camber variant of the same family (-0415) for the same conditions has a lower moment coefficient - about -.11.
2) The NLF(1)-0215 section does have data for a reflexed flap condition however the moment is still fairly high - in the range of -.06 to -.08. The problem though is that when you reflex the flap you shift the lift cure slope but the drag stays fairly consistent. Translated, this means that at cruise (flap reflexed up) the section's l/d actually slightly decreases, but the trim drag goes down too. As such, whether the section is a good candidate would have to be analyzed much more closely than we can do here. The data for these sections can be found in NASA Technical papers #1861 and #1865.
3) For pylon racing you'd need to consider the higher loading and select a section with more camber - the aforementioned 747A315 or the 747A415 might be good candidates, as would several of the NACA laminar sections with similar camber lines, or possibly the similar shaped Riblett foils. All those are characterized by lower moment coefficients: -.02 for the 747A315 and -.03 for the 747A415. The more commonly used 65-415 has a cm.ac of -.055 and the Riblett 37A415 has a coefficient of -.065. Any of these would probably be better than the NLF series.
4) For high speed cruise you really need less camber however the moment coefficient discussion still applies. But here the choice needs to be coupled with an examination of low cl l/d characteristics. Picking a lift coefficient of .1 (arbitrary for this discussion), the NLF sections don't fare all that well with typical values ranging from about 13.5:1 for the -0215 to 15.8:1 for the -0416. The 64-415 is about 19.2:1; the Riblett GA37-315 is 18.2. (Sorry, don't have all the section information readily at hand to get the low camber values)
In short, yes you can make some quick evaluations but for the actual design process, a much closer look is required.