well, 3 factors will come into play (well, more than *3*, but there are 3 *major* contributors all else being equal)
1) Speed: The greater she speed (subsonic) the greater the effect
2) Fin Thickness: The greater the fin thickness the greater the effect
3) Overall thrust time: the longer the burn time, the greater the effect
By all of that I mean (by way of comparison) if you have a model with thin fins with a fast burn motor that only hits a top speed of say 300 MPH (understand, I'm not doing the math here, these are just representations), you may see a small difference (say 200 feet vrs 210 feet) - very hard to tell with the naked eye (or any other naked part of your body
)
But if you had a model with thick fins with a long burn motor and a top speed upwards of 600MPH you would see a significant difference, probably easily decernable with the naked eye (but still not by other naked parts of your body
) (hey, i'm very tired tonight... this is my release... LOL)
Bottom line is there are many things to take into account. Your question was easy to ask, can be very complicated to answer.
A *competitor*
wants those extra 10 feet so he will *always* use the right configuration, regardless.
A sport flier, frankly, does it more for looks than performance. While I've never *reversed* an airfoil, for sport flying I doubt it would have enough of an impact to be concerned with.
Case in point, the following FlisKits kits:
Praetor: sharp angle front and rear of fin
Deuce's Wild!: Flat all edges
A.C.M.E. Spitfire: Flat all edges
Corona: Sharp angle front and rear of fin
Richter Recker: Flat all edges
Cougar 440 & 660 (competition models) airfoil on 1/64" plywood fins (yep!)
So, you can see that *I* don't pay a whole heck of a lot to what is the *best* aerodynamically. Sometimes appearances are more important than performance (ask anyone into saucers about that one...
)
Hope all this rambling helps!
jim