I agree that in most cases the minor errors are negligible. Here's a few pointers: First, pick a cartridge/bullet that is efficient enough for the max range you are interested in. For 500-600 a 308 might be ok, but if you want 800, try a magnum 7mm or 6.5mm.
Second, validate your trajectory (prove your data) with field shooting. Len has a version of our Gseven
ballistics program available on this site that features a simple solver for your true ballistic profile.
Third, be realistic. BDC's are perfect for hunting, but for Ultra Long Range, you will need to apply MOA corrections from a drop chart based on real time variables. Our new G7 Ballistic Turrets have the BDC and MOA numbers so you can have your cake and eat it too!
Finally, with new products coming down the line, BDC's are becoming just as accurate as the Old School MOA correction, with all the benefits of quick, simple adjustment and compensation. The RF we start building in June corrects automatically for incline and air density. It calculates a shoot to range in real time based on your BC and MV (BDC turrets or reticles!).
We train hundreds of guys a year in our Long Range Hunting Courses. I can certify to the ease of learning and application a correct Ballistic Turret will give to Long Range Shooting. By the way, I am very impressed with your "proof" of the errors you will see for different conditions, rather than just relying on forum posts to make your decision.