I am a cupping is the only way to go guy. With that said, I have seen articles on the subject and it's a lot more complicated than just bending the blade tips in. If you buy a cupped prop it probably has gone through adequate testing to ensure it works. If you have a prop shop do it you are in a hit and miss situation I would think. On any combination of boat, engine, prop, load....bla bla bla, you are just speculating until you get it on the water; educated speculation mind you but speculation none the less. Around the Dallas Metroplex James' Propeller Service (now in Carrollton, TX..... just up the road from Big D), has been in business 40+ years and if anyone can guess, and get it right he probably can.