I haven't heard of anyone doing the dilution method for a fas-dpd test, as the primary reason for dilution is to make a test that only goes to 5ppm FC read higher levels such as during shocking. the fas-dpd eliminates the need to do this as it can read really high levels without dilution.
I assume the dilution method will work with the fas-dpd test. you would put in say 5ml of distilled water and 5ml pool water. then test like normal and multiply your FC reading by 2.
the crux of this site is good, reliable testing. this is why the fas-dpd test is harped on. so by purposely losing accuracy when it is unnecessary to lose accuracy, you're kind of going against good testing practices, though you are saving a few dollars on regents in the long run. I use the fas-dpd test daily because my target fc is 8ppm. the money I save by using the methods on this site is about $40/month at the lowest, and I'm guaranteed to not have algae (my opinion based on what I've read here and elsewhere). so to me following the recommendations on this site, including accurate testing as much as possible is worth the extra reagent, even if I was shocking.
there are methods like dilution to push someone through who doesn't have a good test kit and/or fas-dpd test. imo, if you have the fas-dpd test you should get your money's worth out of it by doing the most accurate testing available and not diluting. but you will have to find the happy medium that works best for you.
dang, Jason is up early today!